1. Friction is best defined as:
(A) A force that accelerates objects
(B) A force opposing relative motion between surfaces
(C) A force pulling objects to the center of Earth
(D) A contactless repulsive force
2. The SI unit of friction is:
(A) Joule
(B) Newton
(C) Watt
(D) Pascal
3. Which type of force is friction?
(A) Contact force
(B) Non-contact force
(C) Gravitational force
(D) Nuclear force
4. The coefficient of friction depends on:
(A) Mass of the object
(B) Roughness of surfaces
(C) Velocity of motion
(D) Temperature only
5. The formula for limiting friction is:
(A) F = ma
(B) F = μN
(C) F = Gm₁m₂/r²
(D) F = mv²/r
6. Static friction is:
(A) Friction during motion
(B) Friction before motion starts
(C) Friction in fluids
(D) Zero always
7. Kinetic friction is always:
(A) Greater than static friction
(B) Equal to static friction
(C) Less than static friction
(D) Independent of surface type
8. Which of the following is a beneficial effect of friction?
(A) Wear and tear of shoes
(B) Heat generation in machines
(C) Walking without slipping
(D) Energy loss in engines
9. Which of the following reduces friction?
(A) Rough surfaces
(B) Lubricants
(C) Sandpaper
(D) High pressure
10. Rolling friction is usually:
(A) Greater than static friction
(B) Greater than kinetic friction
(C) Less than sliding friction
(D) Equal to static friction
11. Which type of friction occurs between air and a moving ball?
(A) Static friction
(B) Fluid friction
(C) Rolling friction
(D) Sliding friction
12. Which law explains frictional resistance?
(A) Newton’s First Law
(B) Newton’s Second Law
(C) Newton’s Third Law
(D) Laws of Friction by Amontons and Coulomb
13. A person is able to walk because of:
(A) Gravitational force
(B) Static friction between feet and ground
(C) Inertia
(D) Air resistance
14. The friction between car tires and road provides:
(A) Acceleration
(B) Braking ability
(C) Turning control
(D) All of the above
15. Which factor increases friction between surfaces?
(A) Lubrication
(B) Polishing
(C) Roughening surfaces
(D) Using wheels
16. Friction converts kinetic energy into:
(A) Light energy
(B) Electrical energy
(C) Heat energy
(D) Sound energy only
17. Which type of friction is encountered when starting to push a heavy box?
(A) Rolling friction
(B) Static friction
(C) Kinetic friction
(D) Fluid friction
18. The friction that resists sliding of one solid body over another is called:
(A) Rolling friction
(B) Sliding friction
(C) Fluid friction
(D) Viscous friction
19. Which factor does NOT affect friction?
(A) Normal force
(B) Contact area (ideal case)
(C) Surface roughness
(D) Material type
20. Which of the following is an example of useful friction in the body?
(A) Joint lubrication
(B) Grip during walking
(C) Movement of tendons
(D) All of the above
21. In biomechanics, friction is essential for:
(A) Posture control
(B) Locomotion
(C) Sports performance
(D) All of the above
22. The coefficient of static friction is always:
(A) Less than 1
(B) Greater than kinetic friction
(C) Negative
(D) Zero
23. Which device is used to reduce rolling friction?
(A) Lubricants
(B) Bearings
(C) Sandpaper
(D) Shoes
24. Which type of shoes increase friction for athletes?
(A) Smooth soles
(B) Spiked shoes
(C) Slippers
(D) Sandals
25. The absence of friction would make it impossible to:
(A) Drive a car
(B) Write on paper
(C) Sit on a chair
(D) All of the above
26. Skating is possible due to:
(A) Very high friction
(B) Very low friction on ice
(C) Air resistance
(D) Inertia
27. Which sport requires controlled friction for performance?
(A) Football
(B) Tennis
(C) Gymnastics
(D) All of the above
28. Friction in synovial joints is minimized by:
(A) Synovial fluid
(B) Air
(C) Cartilage only
(D) Bone density
29. Which direction does friction act relative to motion?
(A) Same direction
(B) Opposite direction
(C) Perpendicular
(D) Random
30. The main disadvantage of excessive friction in the body is:
(A) Energy conservation
(B) Tissue wear and tear
(C) Improved grip
(D) Stable posture
31. Car brakes work effectively due to:
(A) Air resistance
(B) Friction between brake pads and wheel
(C) Gravity
(D) Magnetism
32. Rolling resistance in vehicles is minimized by:
(A) Flat tires
(B) Properly inflated tires
(C) Rough roads
(D) Heavy loads
33. Which factor affects sliding friction most strongly?
(A) Mass of object
(B) Contact area directly
(C) Gravitational acceleration
(D) Shape of object
34. Which surface would have the lowest coefficient of friction?
(A) Sandpaper
(B) Ice
(C) Wood
(D) Rubber
35. The grip of a shoe depends largely on:
(A) Frictional force with the ground
(B) Air pressure inside
(C) Elasticity of laces
(D) Sole thickness only
36. Sand is spread on icy roads to:
(A) Reduce friction
(B) Increase friction
(C) Remove ice chemically
(D) Melt ice completely
37. Which condition in humans can result from excessive joint friction?
(A) Arthritis
(B) Asthma
(C) Hypertension
(D) Diabetes
38. The maximum static friction is equal to:
(A) μsN
(B) μkN
(C) μrN
(D) None of the above
39. Which type of motion has the least resistance?
(A) Rolling motion
(B) Sliding motion
(C) Fluid motion
(D) Static motion
40. Kinetic friction force remains:
(A) Constant once motion starts
(B) Zero always
(C) Increasing with time
(D) Randomly changing
41. Excessive friction in machines is reduced by:
(A) Adding lubricants
(B) Increasing roughness
(C) Reducing normal force
(D) Decreasing speed only
42. Which everyday action uses static friction?
(A) Writing with a pen
(B) Brushing teeth
(C) Standing still
(D) All of the above
43. Which of the following is directly proportional to friction?
(A) Mass of object
(B) Normal force
(C) Surface roughness
(D) All of the above
44. Hydroplaning in vehicles happens due to:
(A) Increase in static friction
(B) Loss of friction from water layer
(C) Excessive rolling resistance
(D) High gravity
45. The direction of friction in walking is:
(A) Forward on the ground, backward on the foot
(B) Backward on the ground, forward on the foot
(C) Random
(D) Perpendicular to ground
46. Which natural phenomenon is reduced by friction in air?
(A) Free fall speed of objects
(B) Planetary orbits
(C) Earth’s rotation
(D) Solar radiation
47. The efficiency of mechanical devices is reduced by:
(A) Inertia
(B) Friction
(C) Momentum
(D) Gravity
48. Which material would give the highest shoe-ground traction?
(A) Ice
(B) Rubber
(C) Leather
(D) Glass
49. Proper friction in sports flooring is needed to:
(A) Prevent slipping
(B) Ensure safe stopping
(C) Improve performance
(D) All of the above
50. Friction is essential for:
(A) Movement
(B) Balance
(C) Stability
(D) All of the above