Mechanical properties of fluids MCQs
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1. Which of the following is a property of fluids?
A. Fluids can resist shear stress indefinitely.
B. Fluids have fixed shapes and volumes.
C. Fluids can flow under the action of an external force.
D. Fluids are always incompressible in nature.
Explanation:
A fluid is a substance that can flow and does not resist any shear stress applied to it. Liquids and gases are examples of fluids. They have the ability to deform and take the shape of their container when acted upon by external forces.
Therefore, the correct answer is: C. Fluids can flow under the action of an external force.
A fluid is a substance that can flow and does not resist any shear stress applied to it. Liquids and gases are examples of fluids. They have the ability to deform and take the shape of their container when acted upon by external forces.
Therefore, the correct answer is: C. Fluids can flow under the action of an external force.
2. What is the SI unit of pressure?
A. Torr
B. Pascal (Pa)
C. Bar
D. Newton (N)
Explanation:
Pressure is defined as force per unit area. The SI unit of pressure is the Pascal (Pa), where:
1 Pa = 1 N/m2.
Therefore, the correct answer is: B. Pascal (Pa).
Pressure is defined as force per unit area. The SI unit of pressure is the Pascal (Pa), where:
1 Pa = 1 N/m2.
Therefore, the correct answer is: B. Pascal (Pa).
3. Which property is NOT associated with an ideal fluid?
A. Incompressibility
B. Non-viscosity
C. Turbulent flow
D. Steady flow
Explanation:
An ideal fluid is incompressible, non-viscous, and flows steadily and irrotationally. Turbulent flow is not a property of an ideal fluid.
Therefore, the correct answer is: C. Turbulent flow.
An ideal fluid is incompressible, non-viscous, and flows steadily and irrotationally. Turbulent flow is not a property of an ideal fluid.
Therefore, the correct answer is: C. Turbulent flow.
4. Which branch of physics deals with fluids at rest?
A. Dynamics
B. Hydrostatics
C. Thermodynamics
D. Fluid mechanics
Explanation:
Hydrostatics is the branch of physics that studies fluids at rest and the forces exerted by fluids on surfaces.
Therefore, the correct answer is: B. Hydrostatics.
Hydrostatics is the branch of physics that studies fluids at rest and the forces exerted by fluids on surfaces.
Therefore, the correct answer is: B. Hydrostatics.
5. Which of the following is NOT a property of fluids?
A. Fixed shape
B. Ability to flow
C. Takes the shape of the container
D. Low or zero shear modulus
Explanation:
Fluids lack a fixed shape and take the shape of their container. They have the ability to flow and exhibit a low or zero shear modulus.
Therefore, the correct answer is: A. Fixed shape.
Fluids lack a fixed shape and take the shape of their container. They have the ability to flow and exhibit a low or zero shear modulus.
Therefore, the correct answer is: A. Fixed shape.
6. Which of the following is NOT an example of a fluid?
A. Air
B. Water
C. Molten lava
D. A rigid block of wood
Explanation:
Fluids are substances that can flow, such as liquids, gases, and plasmas. A rigid block of wood does not exhibit these properties.
Therefore, the correct answer is: D. A rigid block of wood.
Fluids are substances that can flow, such as liquids, gases, and plasmas. A rigid block of wood does not exhibit these properties.
Therefore, the correct answer is: D. A rigid block of wood.
7. What type of stress can a fluid not resist?
A. Normal stress
B. Shear stress
C. Tensile stress
D. Compressive stress
Explanation:
Fluids cannot resist shear stress and deform continuously under its action.
Fluids cannot resist shear stress and deform continuously under its action.
8. An ideal fluid is characterized by which of the following properties?
A. Turbulent flow
B. Irrotational flow
C. Compressibility
D. High viscosity
Explanation:
An ideal fluid has irrotational flow, is incompressible, and has no viscosity.
An ideal fluid has irrotational flow, is incompressible, and has no viscosity.
9. Which of these is NOT a property of fluids?
A. High rigidity
B. Ability to flow
C. Permanent deformation
D. Taking the shape of the container
Explanation:
Fluids have no rigidity and can flow and take the shape of their container.
Fluids have no rigidity and can flow and take the shape of their container.
10. What is the equivalent of 1 bar in Pascal?
A. \( 10^5 \, \text{Pa} \)
B. 100 Pa
C. 103 Pa
D. 1 Pa
Explanation:
1 bar is defined as 105 Pascal (Pa).
1 bar is defined as 105 Pascal (Pa).
11. The pressure exerted by a liquid column of height \( h \) with density \( \rho \) is given by:
A. \( p = h^2 \rho g \)
B. \( p = h \rho \)
C. \( p = h \rho g \)
D. \( p = \frac{h}{\rho g} \)
Explanation:
Pressure due to a liquid column is derived as follows:
\[ p = h \rho g \] where \( h \) is the height of the liquid column, \( \rho \) is the density, and \( g \) is the acceleration due to gravity.
Correct answer: \( C. \)
Pressure due to a liquid column is derived as follows:
\[ p = h \rho g \] where \( h \) is the height of the liquid column, \( \rho \) is the density, and \( g \) is the acceleration due to gravity.
Correct answer: \( C. \)
12. Atmospheric pressure at sea level is called:
A. Gauge pressure
B. Normal atmospheric pressure
C. Absolute pressure
D. Hydrostatic pressure
Explanation:
The atmospheric pressure at sea level, which is the standard reference, is called normal atmospheric pressure.
Correct answer: \( B. \)
The atmospheric pressure at sea level, which is the standard reference, is called normal atmospheric pressure.
Correct answer: \( B. \)
13. The pressure inside a liquid at depth \( h \) below the surface is:
A. \( p = p_0 + h \rho g \)
B. \( p = p_0 - h \rho g \)
C. \( p = h \rho g \)
D. \( p = \frac{h \rho g}{p_0} \)
Explanation:
The absolute pressure inside a liquid is given by the formula:
\[ p = p_0 + h \rho g \] where \( p_0 \) is the atmospheric pressure, \( h \) is the depth, \( \rho \) is the density, and \( g \) is the acceleration due to gravity.
Correct answer: \( A. \)
The absolute pressure inside a liquid is given by the formula:
\[ p = p_0 + h \rho g \] where \( p_0 \) is the atmospheric pressure, \( h \) is the depth, \( \rho \) is the density, and \( g \) is the acceleration due to gravity.
Correct answer: \( A. \)
14. The difference between absolute pressure and atmospheric pressure is called:
A. Normal pressure
B. Gauge pressure
C. Hydrostatic pressure
D. Partial pressure
Explanation:
Gauge pressure is the difference between absolute pressure and atmospheric pressure, calculated as:
\[ p_{\text{gauge}} = p - p_0 \] Correct answer: \( B. \)
Gauge pressure is the difference between absolute pressure and atmospheric pressure, calculated as:
\[ p_{\text{gauge}} = p - p_0 \] Correct answer: \( B. \)
15. The atmospheric pressure at a given height decreases because:
A. The density of air increases
B. The height of the air column decreases
C. Gravity decreases with height
D. Air molecules condense
Explanation:
At greater heights, the height of the air column above decreases, leading to a reduction in atmospheric pressure.
Correct answer: \( B. \)
At greater heights, the height of the air column above decreases, leading to a reduction in atmospheric pressure.
Correct answer: \( B. \)
16. The equation \( p = h \rho g \) implies that:
A. Pressure depends on area
B. Pressure is independent of liquid density
C. Pressure is directly proportional to height
D. Pressure decreases with depth
Explanation:
From \( p = h \rho g \), it is evident that pressure increases linearly with the height \( h \) of the liquid column.
Correct answer: \( C. \)
From \( p = h \rho g \), it is evident that pressure increases linearly with the height \( h \) of the liquid column.
Correct answer: \( C. \)
17. A vacuum is defined as:
A. Region with high atmospheric pressure
B. Region where gas pressure is less than atmospheric pressure
C. Region with uniform pressure
D. Region with no pressure
Explanation:
A vacuum is a region where the gas pressure is considerably lower than the atmospheric pressure.
Correct answer: \( B. \)
A vacuum is a region where the gas pressure is considerably lower than the atmospheric pressure.
Correct answer: \( B. \)
18. The pressure in all interconnected vessels is the same because:
A. The vessels are all of the same size
B. The liquid used is the same in all vessels
C. The height of the liquid column is the same in all vessels
D. The shape of the vessels is identical
Explanation:
The pressure at any point in the liquid depends only on the height of the liquid column above it, not on the shape or size of the vessel. Since the height of the liquid is the same, the pressure is uniform across all the vessels.
Correct answer: \( C. \)
The pressure at any point in the liquid depends only on the height of the liquid column above it, not on the shape or size of the vessel. Since the height of the liquid is the same, the pressure is uniform across all the vessels.
Correct answer: \( C. \)
19. Pascal's law states that:
A. Pressure applied on a fluid is transmitted only in the downward direction
B. Pressure applied on a fluid is transmitted to the walls of the container but not to other points of the fluid
C. Pressure applied at any point of a fluid at rest is transmitted equally and undiminished to every point in the fluid and the walls of the container
D. Pressure applied at a point in the fluid is transmitted in a circular motion
Explanation:
Pascal's law states that any pressure applied to an enclosed fluid is transmitted equally and undiminished throughout the fluid and to the walls of the container. This is the basis for hydraulic systems.
Correct answer: \( C. \)
Pascal's law states that any pressure applied to an enclosed fluid is transmitted equally and undiminished throughout the fluid and to the walls of the container. This is the basis for hydraulic systems.
Correct answer: \( C. \)
20. A hydraulic lift works on the principle of:
A. Bernoulli's principle
B. Archimedes' principle
C. Pascal's law
D. Continuity equation
Explanation:
A hydraulic lift operates on Pascal's law, where the pressure applied to a small piston is transmitted to a larger piston, lifting a heavy load with a small force.
Correct answer: \( C. \)
A hydraulic lift operates on Pascal's law, where the pressure applied to a small piston is transmitted to a larger piston, lifting a heavy load with a small force.
Correct answer: \( C. \)
21. In a hydraulic brake system, the force applied to the master cylinder is transmitted to the slave cylinder:
A. Increases the speed of the vehicle
B. Increases the force applied on the slave cylinder
C. Decreases the force applied on the slave cylinder
D. Has no effect on the slave cylinder
Explanation:
The pressure applied to the master cylinder is transmitted undiminished to the slave cylinder, increasing the force applied on the slave cylinder, which then applies a large force to stop the vehicle.
Correct answer: \( B. \)
The pressure applied to the master cylinder is transmitted undiminished to the slave cylinder, increasing the force applied on the slave cylinder, which then applies a large force to stop the vehicle.
Correct answer: \( B. \)
22. In a hydraulic system, if the area of the larger piston is much greater than the area of the smaller piston, then:
A. A small force on the smaller piston can lift a heavy load on the larger piston
B. The pressure on both pistons will be the same, but no work is done
C. The larger piston moves more than the smaller piston
D. The system will not work due to unequal areas
Explanation:
According to Pascal's law, a small force on the smaller piston creates a pressure that is transmitted to the larger piston, lifting a heavy load due to the greater area of the larger piston.
Correct answer: \( A. \)
According to Pascal's law, a small force on the smaller piston creates a pressure that is transmitted to the larger piston, lifting a heavy load due to the greater area of the larger piston.
Correct answer: \( A. \)
23. The pressure at any point in a liquid is dependent on:
A. The shape of the vessel
B. The height of the liquid column above the point
C. The volume of the liquid
D. The amount of liquid in the system
Explanation:
The pressure at any point in a liquid depends only on the height of the liquid column above it. It does not depend on the shape or volume of the container.
Correct answer: \( B. \)
The pressure at any point in a liquid depends only on the height of the liquid column above it. It does not depend on the shape or volume of the container.
Correct answer: \( B. \)
24. The surface layer of a liquid with thickness equal to the range of intermolecular force is called:
A. Surface film
B. Viscous layer
C. Intermolecular film
D. Liquid membrane
Explanation:
The surface film is the layer of a liquid with thickness equal to the range of intermolecular forces, typically appearing between XY and X′Y′.
Correct answer: \( A. \)
The surface film is the layer of a liquid with thickness equal to the range of intermolecular forces, typically appearing between XY and X′Y′.
Correct answer: \( A. \)
25. The surface film of a liquid is characterized by:
A. Uniform pressure distribution
B. No effect of intermolecular forces
C. Thickness equal to the range of intermolecular force
D. Absence of intermolecular interactions
Explanation:
The surface film of a liquid is characterized by having a thickness equal to the range of intermolecular forces, indicating the presence of surface tension effects.
Correct answer: \( C. \)
The surface film of a liquid is characterized by having a thickness equal to the range of intermolecular forces, indicating the presence of surface tension effects.
Correct answer: \( C. \)
26. The surface film of a liquid is influenced by:
A. Gravitational forces only
B. Intermolecular forces
C. External pressure only
D. External temperature only
Explanation:
The surface film of a liquid is primarily influenced by intermolecular forces, which determine the thickness and characteristics of the surface layer.
Correct answer: \( B. \)
The surface film of a liquid is primarily influenced by intermolecular forces, which determine the thickness and characteristics of the surface layer.
Correct answer: \( B. \)
27. The surface film's thickness is determined by:
A. Surface temperature of the liquid
B. Range of intermolecular forces
C. Volume of the liquid
D. Shape of the vessel
Explanation:
The thickness of the surface film in a liquid is governed by the range of intermolecular forces that act between the molecules at the surface.
Correct answer: \( B. \)
The thickness of the surface film in a liquid is governed by the range of intermolecular forces that act between the molecules at the surface.
Correct answer: \( B. \)
28. The surface film is affected by:
A. External mechanical disturbances only
B. Intermolecular forces and external conditions
C. Gravitational forces only
D. None of the above
Explanation:
The surface film of a liquid is affected by intermolecular forces, as well as external conditions like temperature and pressure.
Correct answer: \( B. \)
The surface film of a liquid is affected by intermolecular forces, as well as external conditions like temperature and pressure.
Correct answer: \( B. \)
29. The surface film thickness is not affected by:
A. Temperature of the liquid
B. Volume of the liquid
C. Shape of the container
D. Type of liquid used
Explanation:
The surface film thickness is not directly affected by the shape of the container, though it may still be influenced by intermolecular forces and external conditions.
Correct answer: \( C. \)
The surface film thickness is not directly affected by the shape of the container, though it may still be influenced by intermolecular forces and external conditions.
Correct answer: \( C. \)
30. What does the term "streamline flow" in fluid dynamics refer to?
A. The flow in which fluid particles follow smooth paths without turbulence
B. The chaotic flow of a fluid that results in eddies and vortices
C. The non-uniform flow of fluid in a pipe
D. The flow of a fluid only in one direction
Explanation:
Streamline flow refers to the type of flow where fluid particles move along well-defined paths, called streamlines, without crossing each other. There is no turbulence in this flow, and it is characterized by a smooth and steady motion.
Correct answer: \( A. \)
Streamline flow refers to the type of flow where fluid particles move along well-defined paths, called streamlines, without crossing each other. There is no turbulence in this flow, and it is characterized by a smooth and steady motion.
Correct answer: \( A. \)
31. The surface of a fluid that does not experience any shear stress is called:
A. Surface film
B. Free surface
C. Viscous layer
D. Density layer
Explanation:
The free surface of a fluid is the surface that does not experience any shear stress, such as the interface between water and air.
Correct answer: \( B. \)
The free surface of a fluid is the surface that does not experience any shear stress, such as the interface between water and air.
Correct answer: \( B. \)
32. Molecule B in the surface film experiences:
A. A strong downward cohesive force and weak upward adhesive force
B. Equal forces in all directions
C. Only cohesive forces in the downward direction
D. Only adhesive forces in the upward direction
Explanation:
Molecule B lies within the surface layer and experiences strong downward cohesive forces and weak upward adhesive forces due to the liquid and air interface.
Correct answer: \( A. \)
Molecule B lies within the surface layer and experiences strong downward cohesive forces and weak upward adhesive forces due to the liquid and air interface.
Correct answer: \( A. \)
33. The net cohesive force on molecule C on the surface of the liquid is:
A. Directed outward into the air
B. Directed inward into the liquid
C. Zero
D. Directed upward
Explanation:
Molecule C on the surface experiences a net inward cohesive force due to the higher density of liquid molecules compared to air molecules.
Correct answer: \( C. \)
Molecule C on the surface experiences a net inward cohesive force due to the higher density of liquid molecules compared to air molecules.
Correct answer: \( C. \)
34. The surface film of a liquid behaves like a:
A. Stretched elastic membrane
B. Rigid solid surface
C. Non-stretchable surface
D. Compressed solid membrane
Explanation:
The surface film behaves like a stretched elastic membrane due to the tension acting on it caused by the molecular forces.
Correct answer: \( A. \)
The surface film behaves like a stretched elastic membrane due to the tension acting on it caused by the molecular forces.
Correct answer: \( A. \)
35. Surface tension is defined as:
A. Force per unit volume of the liquid
B. Work done per unit area
C. Pressure difference per unit length
D. Force per unit length acting tangentially to the surface
Explanation:
Surface tension is the force per unit length acting tangentially to the surface of a liquid.
Correct answer: \( A. \)
Surface tension is the force per unit length acting tangentially to the surface of a liquid.
Correct answer: \( A. \)
36. The SI unit of surface tension is:
A. Newton per meter (N/m)
B. Pascal
C. Joule per meter
D. Newton
Explanation:
The SI unit of surface tension is Newton per meter (N/m), which is the force per unit length.
Correct answer: \( A. \)
The SI unit of surface tension is Newton per meter (N/m), which is the force per unit length.
Correct answer: \( A. \)
37. Surface energy is associated with:
A. Molecules inside the liquid
B. Only gas molecules in contact with the liquid
C. Molecules in the surface film of a liquid
D. All molecules in the liquid
Explanation:
Surface energy is the extra potential energy possessed by the molecules in the surface film compared to the molecules inside the liquid.
Correct answer: \( C. \)
Surface energy is the extra potential energy possessed by the molecules in the surface film compared to the molecules inside the liquid.
Correct answer: \( C. \)
38. The work done in stretching a film due to surface tension is stored as:
A. Surface energy
B. Kinetic energy
C. Gravitational potential energy
D. Internal energy
Explanation:
The work done in stretching the film is stored as potential energy in the form of surface energy.
Correct answer: \( A. \)
The work done in stretching the film is stored as potential energy in the form of surface energy.
Correct answer: \( A. \)
39. The relation between surface energy and surface tension is:
A. Surface energy is surface tension per unit area
B. Surface energy is equal to surface tension
C. Surface energy and surface tension are unrelated
D. Surface energy is surface tension multiplied by area
Explanation:
Surface energy is the surface tension per unit area, indicating the energy required to increase the surface area.
Correct answer: \( A. \)
Surface energy is the surface tension per unit area, indicating the energy required to increase the surface area.
Correct answer: \( A. \)
40. The force on a movable arm QR due to surface tension in a film is:
A. \( F = 2L \times T \)
B. \( F = L \times T \)
C. \( F = L^2 \times T \)
D. \( F = T / 2L \)
Explanation:
The force acting on the movable arm QR due to the surface tension in the soap film is given by \( F = 2L \times T \), where \( L \) is the length and \( T \) is the surface tension.
Correct answer: \( A. \)
The force acting on the movable arm QR due to the surface tension in the soap film is given by \( F = 2L \times T \), where \( L \) is the length and \( T \) is the surface tension.
Correct answer: \( A. \)
41. The angle of contact is defined as:
A. The angle between the tangents to the liquid surface and solid surface, measured within the liquid
B. The angle formed by the liquid surface with the vertical wall
C. The angle at which the liquid meets the container
D. The angle formed by cohesive and adhesive forces
Explanation:
The angle of contact is the angle between the tangent drawn to the liquid surface and the solid surface at the point of contact, measured within the liquid.
Correct answer: \( A. \)
The angle of contact is the angle between the tangent drawn to the liquid surface and the solid surface at the point of contact, measured within the liquid.
Correct answer: \( A. \)
42. A concave meniscus is formed when:
A. The angle of contact is acute
B. The angle of contact is obtuse
C. The adhesive force is smaller than the cohesive force
D. The liquid does not wet the solid
Explanation:
A concave meniscus is formed when the angle of contact is acute, as seen in water-glass interfaces.
Correct answer: \( A. \)
A concave meniscus is formed when the angle of contact is acute, as seen in water-glass interfaces.
Correct answer: \( A. \)
43. What happens when the angle of contact is obtuse?
A. A convex meniscus is formed
B. A concave meniscus is formed
C. The liquid wets the solid
D. The adhesive force is greater than the cohesive force
Explanation:
When the angle of contact is obtuse, as in mercury-glass interfaces, a convex meniscus is formed.
Correct answer: \( A. \)
When the angle of contact is obtuse, as in mercury-glass interfaces, a convex meniscus is formed.
Correct answer: \( A. \)
44. What is the angle of contact for a liquid that completely wets a solid surface?
A. \( 0^\circ \)
B. \( 45^\circ \)
C. \( 90^\circ \)
D. \( 180^\circ \)
Explanation:
For a liquid that completely wets a solid surface, such as pure water on clean glass, the angle of contact is nearly \( 0^\circ \).
Correct answer: \( A. \)
For a liquid that completely wets a solid surface, such as pure water on clean glass, the angle of contact is nearly \( 0^\circ \).
Correct answer: \( A. \)
45. What condition is satisfied for an acute angle of contact?
A. \( T_2 - T_1 < T_3 \)
B. \( T_2 - T_1 > T_3 \)
C. \( T_2 > T_1 + T_3 \)
D. \( T_2 = T_1 \)
Explanation:
For an acute angle of contact, \( T_2 - T_1 < T_3 \), where \( T_2 \), \( T_1 \), and \( T_3 \) represent surface tensions at the respective interfaces.
Correct answer: \( A. \)
For an acute angle of contact, \( T_2 - T_1 < T_3 \), where \( T_2 \), \( T_1 \), and \( T_3 \) represent surface tensions at the respective interfaces.
Correct answer: \( A. \)
46. The contact angle of mercury with glass is:
A. \( > 90^\circ \)
B. \( < 90^\circ \)
C. \( = 90^\circ \)
D. \( 0^\circ \)
Explanation:
Mercury does not wet glass, and its contact angle is obtuse, meaning \( > 90^\circ \).
Correct answer: \( A. \)
Mercury does not wet glass, and its contact angle is obtuse, meaning \( > 90^\circ \).
Correct answer: \( A. \)
47. Which of the following is true for a liquid that does not wet a solid?
A. Cohesive force > Adhesive force
B. Cohesive force = Adhesive force
C. Cohesive force < Adhesive force
D. Adhesive force is negligible
Explanation:
A liquid does not wet a solid when the cohesive forces between liquid molecules are greater than the adhesive forces between the liquid and solid molecules.
Correct answer: \( A. \)
A liquid does not wet a solid when the cohesive forces between liquid molecules are greater than the adhesive forces between the liquid and solid molecules.
Correct answer: \( A. \)
48. For a liquid drop on a solid surface, if \( \theta \) is the angle of contact, the surface tension at the solid-liquid interface is given by:
A. \( T_{SL} = T_{SG} - T_{LG} \cos\theta \)
B. \( T_{SL} = T_{LG} + T_{SG} \cos\theta \)
C. \( T_{SL} = T_{SG} + T_{LG} \sin\theta \)
D. \( T_{SL} = T_{LG} - T_{SG} \sin\theta \)
Explanation:
The surface tension at the solid-liquid interface, \( T_{SL} \), is calculated using Young's equation: \( T_{SL} = T_{SG} - T_{LG} \cos\theta \).
Correct answer: \( A. \)
The surface tension at the solid-liquid interface, \( T_{SL} \), is calculated using Young's equation: \( T_{SL} = T_{SG} - T_{LG} \cos\theta \).
Correct answer: \( A. \)
49. Which phenomenon is responsible for the angle of contact?
A. Balance between cohesive and adhesive forces
B. Only cohesive forces
C. Only adhesive forces
D. Gravitational force
Explanation:
The angle of contact arises due to the balance between cohesive forces within the liquid and adhesive forces between the liquid and solid.
Correct answer: \( A. \)
The angle of contact arises due to the balance between cohesive forces within the liquid and adhesive forces between the liquid and solid.
Correct answer: \( A. \)
50. The contact angle of water with a clean glass surface is approximately:
A. \( 0^\circ \)
B. \( 30^\circ \)
C. \( 90^\circ \)
D. \( 180^\circ \)
Explanation:
For water on a clean glass surface, the contact angle is nearly \( 0^\circ \), indicating complete wetting.
Correct answer: \( A. \)
For water on a clean glass surface, the contact angle is nearly \( 0^\circ \), indicating complete wetting.
Correct answer: \( A. \)
51. What happens to the angle of contact when the temperature of the liquid increases?
A. It decreases
B. It increases
C. It remains constant
D. It becomes zero
Explanation:
Any increase in the temperature of a liquid decreases its angle of contact. This is because the cohesive forces within the liquid weaken with an increase in temperature.
Correct answer: \( A. \)
Any increase in the temperature of a liquid decreases its angle of contact. This is because the cohesive forces within the liquid weaken with an increase in temperature.
Correct answer: \( A. \)
52. What is the effect of adding common salt to water on its surface tension?
A. Surface tension increases
B. Surface tension decreases
C. Surface tension remains unchanged
D. Surface tension becomes zero
Explanation:
When soluble substances like sodium chloride (common salt) are dissolved in water, the cohesive forces increase, leading to an increase in surface tension.
Correct answer: \( A. \)
When soluble substances like sodium chloride (common salt) are dissolved in water, the cohesive forces increase, leading to an increase in surface tension.
Correct answer: \( A. \)
53. Why does detergent reduce the surface tension of water?
A. It weakens cohesive forces
B. It strengthens adhesive forces
C. It increases the viscosity of water
D. It alters the density of water
Explanation:
Detergents decrease the surface tension of water by weakening the cohesive forces between water molecules, enabling water to make better contact with surfaces.
Correct answer: \( A. \)
Detergents decrease the surface tension of water by weakening the cohesive forces between water molecules, enabling water to make better contact with surfaces.
Correct answer: \( A. \)
54. What is the effect of impurities on the surface tension of water?
A. Surface tension can either increase or decrease
B. Surface tension always decreases
C. Surface tension always increases
D. Surface tension remains constant
Explanation:
Impurities can either increase or decrease the surface tension of water depending on their nature. Soluble substances like common salt increase it, while sparingly soluble substances like detergent decrease it.
Correct answer: \( A. \)
Impurities can either increase or decrease the surface tension of water depending on their nature. Soluble substances like common salt increase it, while sparingly soluble substances like detergent decrease it.
Correct answer: \( A. \)
55. What is the excess pressure inside a spherical drop as per Laplace's law?
A. \( \frac{2T}{r} \)
B. \( \frac{T}{2r} \)
C. \( 2Tr \)
D. \( \frac{4T}{r} \)
Explanation:
According to Laplace's law of a spherical membrane, the excess pressure inside a spherical drop is given by \( \frac{2T}{r} \), where \( T \) is the surface tension and \( r \) is the radius of the drop.
Correct answer: \( A. \)
According to Laplace's law of a spherical membrane, the excess pressure inside a spherical drop is given by \( \frac{2T}{r} \), where \( T \) is the surface tension and \( r \) is the radius of the drop.
Correct answer: \( A. \)
56. What happens to the angle of contact when the temperature of the liquid increases?
A. It decreases
B. It increases
C. It remains constant
D. It becomes zero
Explanation:
An increase in the temperature of a liquid decreases its angle of contact. This is due to the reduction in cohesive forces as temperature increases.
Correct answer: \( A. \)
An increase in the temperature of a liquid decreases its angle of contact. This is due to the reduction in cohesive forces as temperature increases.
Correct answer: \( A. \)
57. How do soluble impurities, like sodium chloride, affect the surface tension of water?
A. Surface tension increases
B. Surface tension decreases
C. Surface tension remains unchanged
D. Surface tension becomes zero
Explanation:
Soluble impurities like sodium chloride increase the surface tension of water by strengthening the cohesive forces between water molecules.
Correct answer: \( A. \)
Soluble impurities like sodium chloride increase the surface tension of water by strengthening the cohesive forces between water molecules.
Correct answer: \( A. \)
58. What is the effect of insoluble impurities on the surface tension of water?
A. Surface tension decreases
B. Surface tension increases
C. Surface tension remains constant
D. Surface tension becomes zero
Explanation:
Insoluble impurities reduce the surface tension of water by weakening the cohesive forces between water molecules.
Correct answer: \( A. \)
Insoluble impurities reduce the surface tension of water by weakening the cohesive forces between water molecules.
Correct answer: \( A. \)
59. Why is hot water more effective in removing tough stains from fabrics?
A. It has lower surface tension
B. It has higher surface tension
C. It increases the angle of contact
D. It decreases the angle of contact
Explanation:
Hot water has lower surface tension, which improves its ability to penetrate and clean fabrics effectively.
Correct answer: \( A. \)
Hot water has lower surface tension, which improves its ability to penetrate and clean fabrics effectively.
Correct answer: \( A. \)
60. What is the surface tension of a liquid at its critical temperature?
A. Zero
B. Maximum
C. Constant
D. Unchanged
Explanation:
At critical temperature, the surface tension of a liquid becomes zero due to the complete loss of cohesive forces between molecules.
Correct answer: \( A. \)
At critical temperature, the surface tension of a liquid becomes zero due to the complete loss of cohesive forces between molecules.
Correct answer: \( A. \)
61. What is the term for the rise or fall of a liquid inside a narrow tube when it is dipped in the liquid?
A. Capillarity
B. Surface tension
C. Viscosity
D. Adhesion
Explanation:
Capillarity is the phenomenon of rise or fall of a liquid inside a narrow tube due to cohesive and adhesive forces.
Correct answer: \( A. \)
Capillarity is the phenomenon of rise or fall of a liquid inside a narrow tube due to cohesive and adhesive forces.
Correct answer: \( A. \)
62. Which of the following examples demonstrates capillarity in action?
A. Oil rises up the wick of a lamp
B. Surface tension in a droplet
C. Water's high boiling point
D. Viscous drag in honey
Explanation:
Oil rises in the wick due to capillary action, where adhesive forces cause the liquid to rise in narrow spaces.
Correct answer: \( A. \)
Oil rises in the wick due to capillary action, where adhesive forces cause the liquid to rise in narrow spaces.
Correct answer: \( A. \)
63. What happens to the liquid level in a capillary tube when the liquid does not wet the tube’s surface (e.g., mercury in glass)?
A. The liquid level falls
B. The liquid level rises
C. The liquid level remains constant
D. The liquid evaporates
Explanation:
When the liquid does not wet the surface of the tube, the cohesive forces dominate, causing the liquid to experience a capillary fall.
Correct answer: \( A. \)
When the liquid does not wet the surface of the tube, the cohesive forces dominate, causing the liquid to experience a capillary fall.
Correct answer: \( A. \)
64. What is the shape of the meniscus when mercury is placed in a glass capillary?
A. Convex
B. Concave
C. Flat
D. Irregular
Explanation:
Mercury forms a convex meniscus in a glass capillary because it does not wet the surface.
Correct answer: \( A. \)
Mercury forms a convex meniscus in a glass capillary because it does not wet the surface.
Correct answer: \( A. \)
65. Which factor determines the height to which a liquid rises or falls in a capillary tube?
A. Radius of the capillary
B. Surface area of the liquid
C. Viscosity of the liquid
D. Volume of the liquid
Explanation:
The height of rise or fall in a capillary tube is inversely proportional to the radius of the tube, as given by \( h \propto \frac{1}{r} \).
Correct answer: \( A. \)
The height of rise or fall in a capillary tube is inversely proportional to the radius of the tube, as given by \( h \propto \frac{1}{r} \).
Correct answer: \( A. \)
66. What is the value of the angle of contact for a liquid that wets the surface of a capillary tube?
A. Acute
B. Obtuse
C. Right angle
D. Zero
Explanation:
For a liquid that wets the surface, the angle of contact is acute, facilitating the rise in the capillary.
Correct answer: \( A. \)
For a liquid that wets the surface, the angle of contact is acute, facilitating the rise in the capillary.
Correct answer: \( A. \)
67. What is the branch of physics that studies the properties of fluids in motion called?
A. Fluid Mechanics
B. Hydrodynamics
C. Thermodynamics
D. Aerodynamics
Explanation:
The study of properties of fluids in motion is called Hydrodynamics.
Correct answer: \( B. \)
The study of properties of fluids in motion is called Hydrodynamics.
Correct answer: \( B. \)
68. In a steady flow, what property of the fluid remains constant at a given point over time?
A. Density
B. Pressure
C. Velocity
D. All of the above
Explanation:
In a steady flow, measurable properties like density, pressure, and velocity remain constant at a given point over time.
Correct answer: \( D. \)
In a steady flow, measurable properties like density, pressure, and velocity remain constant at a given point over time.
Correct answer: \( D. \)
69. What term describes the path of an individual particle in a moving fluid?
A. Flow line
B. Streamline
C. Flow tube
D. Critical line
Explanation:
The path followed by an individual particle in a moving fluid is called a flow line.
Correct answer: \( A. \)
The path followed by an individual particle in a moving fluid is called a flow line.
Correct answer: \( A. \)
70. What is the velocity beyond which a streamline flow becomes turbulent called?
A. Terminal velocity
B. Critical velocity
C. Escape velocity
D. Average velocity
Explanation:
The velocity beyond which a streamline flow becomes turbulent is called critical velocity.
Correct answer: \( B. \)
The velocity beyond which a streamline flow becomes turbulent is called critical velocity.
Correct answer: \( B. \)
71. What is the Reynolds number used to differentiate?
A. Streamline flow and turbulent flow
B. Viscous and non-viscous fluids
C. Liquid and gaseous fluids
D. Laminar and critical flows
Explanation:
The Reynolds number is used to differentiate between streamline and turbulent flows.
Correct answer: \( A. \)
The Reynolds number is used to differentiate between streamline and turbulent flows.
Correct answer: \( A. \)
72. Which property of a fluid causes the relative motion between layers to experience a dragging force?
A. Density
B. Surface tension
C. Viscosity
D. Compressibility
Explanation:
Viscosity is the property of a fluid that causes the relative motion between layers to experience a dragging force.
Correct answer: \( C. \)
Viscosity is the property of a fluid that causes the relative motion between layers to experience a dragging force.
Correct answer: \( C. \)
73. What is the viscosity of an ideal fluid?
A. Zero
B. Very high
C. Infinity
D. Variable
Explanation:
An ideal fluid has zero viscosity, meaning there is no internal friction between fluid layers.
Correct answer: \( A. \)
An ideal fluid has zero viscosity, meaning there is no internal friction between fluid layers.
Correct answer: \( A. \)
74. The coefficient of viscosity is defined as the viscous force per unit area per unit of which of the following?
A. Velocity gradient
B. Velocity
C. Area
D. Mass
Explanation:
The coefficient of viscosity is defined as the viscous force per unit area per unit velocity gradient, which gives us a measure of the internal friction in a fluid.
Correct answer: \( A. \)
The coefficient of viscosity is defined as the viscous force per unit area per unit velocity gradient, which gives us a measure of the internal friction in a fluid.
Correct answer: \( A. \)
75. According to Stokes' Law, the viscous force acting on a small sphere is proportional to which of the following factors?
A. Radius of the sphere, velocity, and coefficient of viscosity
B. Only the velocity of the sphere
C. Only the radius of the sphere
D. Only the coefficient of viscosity
Explanation:
Stokes' Law states that the viscous force acting on a small sphere falling through a fluid is proportional to the radius of the sphere, its velocity through the fluid, and the coefficient of viscosity of the fluid.
Correct answer: \( A. \)
Stokes' Law states that the viscous force acting on a small sphere falling through a fluid is proportional to the radius of the sphere, its velocity through the fluid, and the coefficient of viscosity of the fluid.
Correct answer: \( A. \)
76. What is the role of the buoyant force when a spherical object falls through a viscous fluid?
A. It increases the speed of the object
B. It reduces the downward velocity of the object
C. It maintains the constant velocity of the object
D. It has no effect on the velocity of the object
Explanation:
The buoyant force acts upwards and opposes the downward motion of the spherical object, contributing to the terminal velocity when balanced with the gravitational force and viscous drag.
Correct answer: \( B. \)
The buoyant force acts upwards and opposes the downward motion of the spherical object, contributing to the terminal velocity when balanced with the gravitational force and viscous drag.
Correct answer: \( B. \)
77. When does the downward velocity of a spherical object falling through a viscous fluid become constant?
A. When the net force becomes zero
B. When the object's weight increases
C. When the object's radius decreases
D. When the object's velocity decreases
Explanation:
The downward velocity becomes constant when the net downward force is zero, meaning the gravitational force is balanced by the viscous drag and buoyant forces, resulting in terminal velocity.
Correct answer: \( A. \)
The downward velocity becomes constant when the net downward force is zero, meaning the gravitational force is balanced by the viscous drag and buoyant forces, resulting in terminal velocity.
Correct answer: \( A. \)
78. What does the equation of continuity for fluid flow state?
A. The mass of fluid entering a section is not equal to the mass leaving
B. The velocity of the fluid remains constant in all sections of the tube
C. The fluid can be compressed within the tube
D. The product of cross-sectional area and velocity is constant
Explanation:
The equation of continuity states that for an incompressible fluid, the mass flow rate is constant, and thus \( A_1 v_1 = A_2 v_2 \), where \( A \) is the cross-sectional area and \( v \) is the velocity.
Correct answer: \( D. \)
The equation of continuity states that for an incompressible fluid, the mass flow rate is constant, and thus \( A_1 v_1 = A_2 v_2 \), where \( A \) is the cross-sectional area and \( v \) is the velocity.
Correct answer: \( D. \)
79. What is the value of the terminal velocity for an object falling through a viscous fluid?
A. It is when the net force acting on the object becomes zero
B. It is when the weight of the object is maximum
C. It is when the object is at rest
D. It is when the object's velocity becomes constant
Explanation:
Terminal velocity is achieved when the downward gravitational force is balanced by the upward viscous drag and buoyant forces, resulting in zero net force.
Correct answer: \( A. \)
Terminal velocity is achieved when the downward gravitational force is balanced by the upward viscous drag and buoyant forces, resulting in zero net force.
Correct answer: \( A. \)
80. In which of the following situations is the Reynolds number greater than 2000, indicating turbulent flow?
A. When the fluid flows at high velocity and with large characteristic length
B. When the fluid flows at low velocity and with small characteristic length
C. When the fluid is incompressible and has low viscosity
D. When the fluid is flowing through a narrow pipe
Explanation:
A Reynolds number greater than 2000 typically indicates turbulent flow, which occurs when the velocity is high, and the characteristic length (e.g., pipe diameter) is large.
Correct answer: \( A. \)
A Reynolds number greater than 2000 typically indicates turbulent flow, which occurs when the velocity is high, and the characteristic length (e.g., pipe diameter) is large.
Correct answer: \( A. \)
81. What is the main characteristic of a viscous fluid?
A. It resists the relative motion between adjacent layers of the fluid
B. It flows without resistance between layers
C. It is incompressible under normal conditions
D. It has no effect on the motion of objects
Explanation:
A viscous fluid resists the relative motion between its layers, leading to a force that opposes the flow of the fluid.
Correct answer: \( A. \)
A viscous fluid resists the relative motion between its layers, leading to a force that opposes the flow of the fluid.
Correct answer: \( A. \)
82. The buoyant force on an object submerged in a fluid depends on which of the following?
A. The volume of the displaced fluid
B. The density of the object
C. The temperature of the object
D. The surface area of the object
Explanation:
The buoyant force is equal to the weight of the displaced fluid, which depends on the volume of the fluid displaced by the object.
Correct answer: \( A. \)
The buoyant force is equal to the weight of the displaced fluid, which depends on the volume of the fluid displaced by the object.
Correct answer: \( A. \)
83. What does the equation \( F = \eta \cdot A \cdot \frac{v}{d} \) represent?
A. The viscous force on a fluid in motion
B. The force exerted by an object in motion
C. The drag force on an object moving through air
D. The buoyant force on a submerged object
Explanation:
The equation \( F = \eta \cdot A \cdot \frac{v}{d} \) is known as the viscous force equation, where \( F \) is the viscous force, \( \eta \) is the coefficient of viscosity, \( A \) is the area, \( v \) is the velocity, and \( d \) is the distance between layers of the fluid.
Correct answer: \( A. \)
The equation \( F = \eta \cdot A \cdot \frac{v}{d} \) is known as the viscous force equation, where \( F \) is the viscous force, \( \eta \) is the coefficient of viscosity, \( A \) is the area, \( v \) is the velocity, and \( d \) is the distance between layers of the fluid.
Correct answer: \( A. \)
84. What does Bernoulli's principle explain?
A. The relationship between the velocity and pressure of a fluid
B. The conservation of mass in fluids
C. The buoyant force on an object submerged in a fluid
D. The drag force on an object moving through a fluid
Explanation:
Bernoulli's principle states that an increase in the speed of a fluid occurs simultaneously with a decrease in pressure or a decrease in the fluid's potential energy. It explains the relationship between velocity and pressure in a fluid flow.
Correct answer: \( A. \)
Bernoulli's principle states that an increase in the speed of a fluid occurs simultaneously with a decrease in pressure or a decrease in the fluid's potential energy. It explains the relationship between velocity and pressure in a fluid flow.
Correct answer: \( A. \)
85. What is the equation of continuity in fluid mechanics?
A. \( A_1 v_1 = A_2 v_2 \)
B. \( p_1 v_1 = p_2 v_2 \)
C. \( A_1 p_1 = A_2 p_2 \)
D. \( v_1 + v_2 = v_3 \)
Explanation:
The equation of continuity states that for an incompressible fluid, the product of the cross-sectional area and velocity at any point is constant. Hence, \( A_1 v_1 = A_2 v_2 \), where \( A_1 \) and \( A_2 \) are the cross-sectional areas and \( v_1 \) and \( v_2 \) are the fluid velocities at those points.
Correct answer: \( A. \)
The equation of continuity states that for an incompressible fluid, the product of the cross-sectional area and velocity at any point is constant. Hence, \( A_1 v_1 = A_2 v_2 \), where \( A_1 \) and \( A_2 \) are the cross-sectional areas and \( v_1 \) and \( v_2 \) are the fluid velocities at those points.
Correct answer: \( A. \)
86. What does the Venturi effect describe?
A. The increase in velocity and decrease in pressure as a fluid flows through a constriction
B. The reduction in velocity as fluid exits an orifice
C. The relationship between pressure and volume in a fluid
D. The effect of gravity on a flowing fluid
Explanation:
The Venturi effect describes how the velocity of a fluid increases when passing through a constriction in a pipe or tube, leading to a decrease in pressure according to Bernoulli's principle.
Correct answer: \( A. \)
The Venturi effect describes how the velocity of a fluid increases when passing through a constriction in a pipe or tube, leading to a decrease in pressure according to Bernoulli's principle.
Correct answer: \( A. \)
87. What is the speed of efflux of a liquid flowing out from an orifice according to Torricelli's law?
A. \( v = \sqrt{2gh} \)
B. \( v = \sqrt{gh} \)
C. \( v = 2gh \)
D. \( v = gh \)
Explanation:
According to Torricelli's law, the speed of efflux (velocity of liquid flowing out of an orifice) is given by \( v = \sqrt{2gh} \), where \( g \) is the acceleration due to gravity and \( h \) is the height of the liquid above the orifice.
Correct answer: \( A. \)
According to Torricelli's law, the speed of efflux (velocity of liquid flowing out of an orifice) is given by \( v = \sqrt{2gh} \), where \( g \) is the acceleration due to gravity and \( h \) is the height of the liquid above the orifice.
Correct answer: \( A. \)
88. Which of the following is a practical application of Bernoulli’s principle?
A. The lift on airplane wings
B. The upward force on a submerged object in water
C. The pressure increase in a pipe constriction
D. The fluid flowing from high to low pressure
Explanation:
Bernoulli's principle is used in the design of airplane wings, where faster airflow over the top of the wing causes a decrease in pressure, resulting in lift that allows the plane to fly.
Correct answer: \( A. \)
Bernoulli's principle is used in the design of airplane wings, where faster airflow over the top of the wing causes a decrease in pressure, resulting in lift that allows the plane to fly.
Correct answer: \( A. \)
89. What is the principle behind the operation of a hydraulic press?
A. Pascal's law
B. Archimedes' principle
C. Bernoulli's principle
D. Law of conservation of energy
Explanation:
The hydraulic press operates based on Pascal's law, which states that when pressure is applied to a confined fluid, the pressure is transmitted equally in all directions. This principle allows the hydraulic press to lift heavy objects with a relatively small force.
Correct answer: \( A. \)
The hydraulic press operates based on Pascal's law, which states that when pressure is applied to a confined fluid, the pressure is transmitted equally in all directions. This principle allows the hydraulic press to lift heavy objects with a relatively small force.
Correct answer: \( A. \)
90. What does the term "streamline flow" in fluid dynamics refer to?
A. The flow in which fluid particles follow smooth paths without turbulence
B. The chaotic flow of a fluid that results in eddies and vortices
C. The non-uniform flow of fluid in a pipe
D. The flow of a fluid only in one direction
Explanation:
Streamline flow refers to the type of flow where fluid particles move along well-defined paths, called streamlines, without crossing each other. There is no turbulence in this flow, and it is characterized by a smooth and steady motion.
Correct answer: \( A. \)
Streamline flow refers to the type of flow where fluid particles move along well-defined paths, called streamlines, without crossing each other. There is no turbulence in this flow, and it is characterized by a smooth and steady motion.
Correct answer: \( A. \)
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