AP ECET PHYSICS Multiple Choice Questions (MCQs)

46. The force that resists the relative motion of two surfaces in contact is called:

• a) Tension
• b) Friction
• c) Normal reaction
• d) Gravity

Answer: b) Friction

47. The normal reaction is:

• a) Always equal to the force of friction
• b) The force exerted by a surface perpendicular to the object
• c) The same as the weight of the object
• d) None of the above

Answer: b) The force exerted by a surface perpendicular to the object

48. Which of the following is not a type of friction?

• a) Static friction
• b) Kinetic friction
• c) Rolling friction
• d) Gravitational friction

Answer: d) Gravitational friction

49. The coefficient of friction is:

• a) The ratio of the frictional force to the normal reaction force
• b) The ratio of the weight of the object to the normal force
• c) The ratio of the normal force to the weight of the object
• d) None of the above

Answer: a) The ratio of the frictional force to the normal reaction force

50. The angle of friction is:

• a) The angle between the normal reaction and the frictional force
• b) The angle between the force applied and the surface
• c) The angle at which the body starts to move
• d) The angle at which friction becomes maximum

Answer: a) The angle between the normal reaction and the frictional force

51. Which of the following methods can reduce friction?

• a) Lubrication
• b) Polishing the surface
• c) Using rollers
• d) All of the above

Answer: d) All of the above

52. Which of the following is an advantage of friction?

• a) It wears out mechanical parts
• b) It reduces efficiency in machines
• c) It helps in walking and driving
• d) It causes heat generation

Answer: c) It helps in walking and driving

53. The frictional force between two surfaces depends on:

• a) The weight of the object
• b) The type of surfaces in contact
• c) The roughness of the surfaces
• d) All of the above

Answer: d) All of the above

54. Which of the following reduces friction in machine parts?

• a) Rough surfaces
• b) Polished surfaces
• c) Sticky surfaces
• d) None of the above

Answer: b) Polished surfaces

55. A body is placed on a smooth inclined plane. The frictional force acting on the body is:

• a) Zero
• b) Equal to the weight of the body
• c) Equal to the normal reaction
• d) Dependent on the angle of inclination

Answer: a) Zero

56. In case of motion on a rough inclined plane, the frictional force is:

• a) Equal to the component of weight along the plane
• b) Opposite to the direction of motion
• c) Proportional to the normal reaction
• d) All of the above

Answer: d) All of the above

57. The maximum static friction is given by:

• a) \( \mu_s \times N \)
• b) \( \mu_k \times N \)
• c) \( \mu_s \times m \)
• d) None of the above

Answer: a) \( \mu_s \times N \)

58. The frictional force on a body is always:

• a) Equal to the normal reaction force
• b) Opposite to the direction of motion
• c) Less than the normal reaction force
• d) Always zero

Answer: b) Opposite to the direction of motion

59. If the coefficient of friction is 0.3 and the normal force is 200 N, the frictional force is:

• a) 60 N
• b) 0.6 N
• c) 30 N
• d) 200 N

Answer: a) 60 N

60. The limiting friction is the frictional force acting when:

• a) The object is at rest and no external force is applied
• b) The object is in motion
• c) The object is on the verge of motion
• d) The object is moving with constant velocity

Answer: c) The object is on the verge of motion