Friction Part 1: MCQs (Q1–Q25)
🌀 Friction – MCQs for Class 8 Science
Part 1: Q1–Q25
Q1. Friction is a type of:
A) Contact force
B) Non-contact force
C) Muscular force
D) Magnetic force
✅ Correct Answer: A) Contact force
Explanation:
- A) ✔ Friction arises when two surfaces are in contact.
- B) Non-contact → gravity, magnetism.
- C, D – Different forces.
Q2. Friction always acts:
A) In the direction of motion
B) Opposite to the direction of motion
C) At an angle of 90° to motion
D) Along the force applied
✅ Correct Answer: B) Opposite to the direction of motion
Explanation:
- A, C, D – Incorrect.
- B) ✔ Friction resists relative motion.
Q3. The force that opposes motion between two surfaces is called:
A) Gravity
B) Thrust
C) Friction
D) Pressure
✅ Correct Answer: C) Friction
Explanation:
- A, B, D – Not resistance forces.
- C) ✔ Friction is resistive force.
Q4. The main cause of friction is:
A) Smooth surfaces
B) Irregularities on surfaces
C) Pressure applied
D) Weight of object
✅ Correct Answer: B) Irregularities on surfaces
Explanation:
- B) ✔ Microscopic irregularities interlock → friction.
- A, C, D – Contribute but not main cause.
Q5. Friction is maximum when an object is:
A) Stationary
B) Just moving
C) Moving fast
D) In air
✅ Correct Answer: A) Stationary
Explanation:
- A) ✔ Static friction > sliding > rolling.
- B, C – Smaller friction.
- D – Not relevant.
Q6. The frictional force that acts when an object is just about to move is called:
A) Sliding friction
B) Rolling friction
C) Limiting friction
D) Dynamic friction
✅ Correct Answer: C) Limiting friction
Explanation:
- C) ✔ Limiting friction = maximum static friction before motion begins.
Q7. Sliding friction is usually:
A) More than static friction
B) Less than static friction
C) Equal to static friction
D) Zero
✅ Correct Answer: B) Less than static friction
Explanation:
- B) ✔ Once in motion, interlocking reduces → less force required.
Q8. Rolling friction is:
A) Greater than sliding friction
B) Lesser than sliding friction
C) Equal to sliding friction
D) Independent of surface
✅ Correct Answer: B) Lesser than sliding friction
Explanation:
- B) ✔ Wheels reduce surface contact → rolling friction least.
Q9. Which of the following reduces friction?
A) Rough surfaces
B) Sand
C) Lubricants
D) Increase in load
✅ Correct Answer: C) Lubricants
Explanation:
- C) ✔ Lubricants fill irregularities → smoother motion.
Q10. Which of the following is a disadvantage of friction?
A) Helps us walk
B) Causes wear and tear
C) Helps in stopping vehicles
D) Used in matchsticks
✅ Correct Answer: B) Causes wear and tear
Explanation:
- B) ✔ Constant rubbing damages parts.
Q11. Friction is desirable in:
A) Machine parts
B) Walking
C) Engines
D) Bearings
✅ Correct Answer: B) Walking
Explanation:
- B) ✔ Friction provides grip while walking.
Q12. Which of these uses fluid friction?
A) Bicycle tyre
B) Brakes
C) Oil in machines
D) Footwear
✅ Correct Answer: C) Oil in machines
Explanation:
- C) ✔ Oil reduces solid friction by replacing it with fluid friction.
Q13. Fluid friction is also called:
A) Static friction
B) Sliding friction
C) Drag
D) Rolling friction
✅ Correct Answer: C) Drag
Explanation:
- C) ✔ Resistive force in fluids = drag.
Q14. Air resistance is an example of:
A) Static friction
B) Rolling friction
C) Fluid friction
D) Limiting friction
✅ Correct Answer: C) Fluid friction
Explanation:
- C) ✔ Air = fluid, offers resistive drag.
Q15. The shape of an aeroplane is designed to:
A) Increase drag
B) Reduce air resistance
C) Increase weight
D) Increase thrust
✅ Correct Answer: B) Reduce air resistance
Explanation:
- B) ✔ Streamlined body reduces drag.
Q16. Which of the following is used to reduce friction in heavy machinery?
A) Grease
B) Sand
C) Water
D) Rough surfaces
✅ Correct Answer: A) Grease
Explanation:
- A) ✔ Grease lubricates surfaces.
Q17. Which of the following increases friction?
A) Oil
B) Grease
C) Polishing
D) Sand on icy road
✅ Correct Answer: D) Sand on icy road
Explanation:
- D) ✔ Rough particles increase grip.
Q18. Ball bearings are used to:
A) Increase friction
B) Reduce rolling friction
C) Increase sliding friction
D) Increase weight
✅ Correct Answer: B) Reduce rolling friction
Explanation:
- B) ✔ Ball bearings convert sliding into rolling friction.
Q19. Which of these is NOT true about friction?
A) It always opposes motion
B) It produces heat
C) It can be removed completely
D) It helps in walking
✅ Correct Answer: C) It can be removed completely
Explanation:
- C) ✔ Friction can be reduced, never eliminated.
Q20. Matchsticks catch fire due to:
A) Gravity
B) Friction
C) Lubrication
D) Magnetism
✅ Correct Answer: B) Friction
Explanation:
- B) ✔ Rubbing match against rough surface → heat → ignition.
Q21. Which has least friction?
A) Sliding
B) Rolling
C) Static
D) Limiting
✅ Correct Answer: B) Rolling
Explanation:
- B) ✔ Rolling friction is least among all.
Q22. The force of friction depends on:
A) Nature of surface
B) Weight of object
C) Normal force
D) All of these
✅ Correct Answer: D) All of these
Explanation:
- D) ✔ Friction depends on surface roughness, load, and contact force.
Q23. The advantage of friction is:
A) Produces heat in machines
B) Causes wear and tear
C) Allows writing with pencil
D) Reduces efficiency
✅ Correct Answer: C) Allows writing with pencil
Explanation:
- C) ✔ Writing is possible due to grip between pencil and paper.
Q24. The footwear of athletes is provided with spikes to:
A) Reduce weight
B) Increase friction
C) Reduce friction
D) Increase smoothness
✅ Correct Answer: B) Increase friction
Explanation:
- B) ✔ More grip = better running control.
Q25. Friction converts mechanical energy into:
A) Chemical energy
B) Heat energy
C) Electrical energy
D) Magnetic energy
✅ Correct Answer: B) Heat energy
Explanation:
- B) ✔ Rubbing → heat generated.
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