1. Friction is a force that
A) Pulls objects downward
B) Opposes motion between two surfaces
C) Increases motion
D) Acts only on moving objects
Answer: B
2. The type of friction that acts on stationary objects is called
A) Kinetic friction
B) Static friction
C) Rolling friction
D) Fluid friction
Answer: B
3. Which factor does NOT affect friction?
A) Surface roughness
B) Normal force
C) Color of the object
D) Type of material
Answer: C
4. Which friction is usually the greatest?
A) Static friction
B) Sliding friction
C) Rolling friction
D) Fluid friction
Answer: A
5. Which of the following reduces friction?
A) Lubrication
B) Roughening surfaces
C) Increasing weight
D) Increasing pressure
Answer: A
6. Friction always
A) Accelerates motion
B) Opposes motion
C) Pulls objects upward
D) Increases energy
Answer: B
7. Rolling friction is generally
A) Greater than sliding friction
B) Equal to sliding friction
C) Less than sliding friction
D) Zero
Answer: C
8. Friction converts kinetic energy into
A) Potential energy
B) Light energy
C) Heat energy
D) Sound energy only
Answer: C
9. Which of the following has the least friction?
A) Ice on ice
B) Rubber on concrete
C) Wood on wood
D) Metal on metal
Answer: A
10. Kinetic friction occurs when
A) Objects are at rest
B) Objects are moving
C) Objects are flying
D) Objects are stationary
Answer: B
11. The coefficient of friction depends on
A) Velocity of motion
B) Nature of surfaces in contact
C) Color of the surface
D) Size of the object only
Answer: B
12. Friction is a necessary force because it
A) Stops objects completely
B) Allows walking without slipping
C) Acts only on liquids
D) Decreases energy
Answer: B
13. Sliding friction is usually
A) Greater than static friction
B) Equal to rolling friction
C) Less than static friction
D) Independent of surfaces
Answer: C
14. Fluid friction occurs when
A) Objects slide on solid surfaces
B) Objects roll on wheels
C) Objects move through liquids or gases
D) Objects are at rest
Answer: C
15. Which of the following increases friction?
A) Oil
B) Water
C) Sandpaper
D) Lubricant
Answer: C
16. Friction is measured in
A) Newtons
B) Joules
C) Meters
D) Watts
Answer: A
17. The force opposing motion between tires and road is called
A) Gravitational force
B) Frictional force
C) Magnetic force
D) Tension
Answer: B
18. In which situation is friction useful?
A) Sliding a book on ice
B) Moving a car on a muddy road
C) Walking on a rough road
D) All of the above
Answer: C
19. Which statement is correct?
A) Friction acts in the same direction as motion
B) Friction acts opposite to motion
C) Friction acts only in liquids
D) Friction always decreases energy
Answer: B
20. Which of the following reduces wear and tear on machinery?
A) Increasing friction
B) Lubrication
C) Increasing pressure
D) Roughening surfaces
Answer: B
21. When a block slides on a table, the friction acting on it is
A) Static friction
B) Kinetic friction
C) Rolling friction
D) Magnetic friction
Answer: B
22. The force of friction is directly proportional to
A) Speed of object
B) Normal force
C) Volume of object
D) Surface color
Answer: B
23. Friction is always caused by
A) Magnetic fields
B) Surface irregularities
C) Gravity only
D) Pressure alone
Answer: B
24. A ball rolling on a smooth floor experiences
A) Maximum static friction
B) Minimum rolling friction
C) Maximum sliding friction
D) No friction at all
Answer: B
25. Friction can be eliminated completely
A) On rough surfaces
B) On ice
C) In a vacuum
D) On water
Answer: C
26. Which type of friction is responsible for brakes stopping a car?
A) Static friction
B) Rolling friction
C) Sliding friction
D) Fluid friction
Answer: C
27. Which of the following surfaces has the highest coefficient of friction?
A) Ice
B) Rubber on concrete
C) Teflon on steel
D) Oil on metal
Answer: B
28. The frictional force always acts
A) In the direction of motion
B) Opposite to motion
C) Perpendicular to motion
D) None of the above
Answer: B
29. Friction generates heat because
A) Kinetic energy is converted to thermal energy
B) Objects stop completely
C) Surfaces repel each other
D) Surfaces attract each other
Answer: A
30. Rolling friction is important in
A) Walking
B) Driving a car
C) Sliding a box
D) Flying an airplane
Answer: B