Friction Part 4: MCQs (Q76–Q100)
🌀 Friction – MCQs for Class 8 Science
Part 4: Q76–Q100
Q76. Which type of friction helps us to hold objects firmly?
A) Rolling friction
B) Static friction
C) Sliding friction
D) Fluid friction
✅ Correct Answer: B) Static friction
Explanation:
- B) ✔ Grip while holding objects comes from static friction.
- A, C, D – Not correct.
Q77. Which type of friction acts on a bicycle moving in air?
A) Static friction
B) Fluid friction
C) Rolling friction
D) Sliding friction
✅ Correct Answer: B) Fluid friction
Explanation:
- B) ✔ Air offers resistance, a form of fluid friction.
Q78. The opposing force to motion in liquids is called:
A) Resistance
B) Fluid friction
C) Buoyant force
D) Pressure
✅ Correct Answer: B) Fluid friction
Explanation:
- B) ✔ Also called drag.
Q79. Which factor reduces friction between two surfaces?
A) Roughness
B) Lubrication
C) Increase in weight
D) Adding sand
✅ Correct Answer: B) Lubrication
Explanation:
- B) ✔ Oil/grease fills irregularities → smoother motion.
Q80. The streamlined shape of birds helps in:
A) Reducing friction of air
B) Increasing grip
C) Reducing weight
D) Generating heat
✅ Correct Answer: A) Reducing friction of air
Explanation:
- A) ✔ Streamlined body reduces drag.
Q81. Which type of friction is least?
A) Static
B) Sliding
C) Rolling
D) Limiting
✅ Correct Answer: C) Rolling
Explanation:
- C) ✔ Rolling friction is smallest of all.
Q82. Which type of friction acts between shoes and ground while walking?
A) Rolling
B) Static
C) Sliding
D) Fluid
✅ Correct Answer: B) Static
Explanation:
- B) ✔ Foot pushes ground, static friction prevents slipping.
Q83. Which of these is NOT a way to reduce friction?
A) Lubrication
B) Polishing
C) Ball bearings
D) Roughening surface
✅ Correct Answer: D) Roughening surface
Explanation:
- D) ✔ Roughness increases friction.
Q84. Which of these is NOT an effect of friction?
A) Produces heat
B) Produces wear
C) Produces noise
D) Increases mass
✅ Correct Answer: D) Increases mass
Explanation:
- D) ✔ Friction does not affect mass.
Q85. Why do parachutes open during fall?
A) To increase weight
B) To increase air drag
C) To reduce weight
D) To reduce air pressure
✅ Correct Answer: B) To increase air drag
Explanation:
- B) ✔ Larger area → more air resistance → slower fall.
Q86. Which surface will have the lowest friction?
A) Glass on glass
B) Wood on wood
C) Rough concrete
D) Rubber on road
✅ Correct Answer: A) Glass on glass
Explanation:
- A) ✔ Smooth polished surfaces → least resistance.
Q87. Which friction is useful in writing with a pen?
A) Static friction
B) Sliding friction
C) Rolling friction
D) Fluid friction
✅ Correct Answer: B) Sliding friction
Explanation:
- B) ✔ Pen rubs on paper, leaving ink due to sliding friction.
Q88. Which is a disadvantage of friction in machines?
A) It allows movement
B) It reduces efficiency
C) It provides grip
D) It helps in braking
✅ Correct Answer: B) It reduces efficiency
Explanation:
- B) ✔ Heat and wear reduce efficiency.
Q89. Why do vehicle tyres have treads?
A) To reduce noise
B) To increase friction
C) To reduce grip
D) To increase speed
✅ Correct Answer: B) To increase friction
Explanation:
- B) ✔ Treads grip road → avoid slipping.
Q90. Why do mountain climbers use shoes with spikes?
A) To look stylish
B) To reduce friction
C) To increase friction
D) To reduce weight
✅ Correct Answer: C) To increase friction
Explanation:
- C) ✔ Spikes provide better grip on slippery surfaces.
Q91. When does limiting friction act?
A) After body starts moving
B) Before motion starts
C) During uniform motion
D) Only in liquids
✅ Correct Answer: B) Before motion starts
Explanation:
- B) ✔ Limiting friction is maximum static friction.
Q92. Which type of friction acts when tyres roll without slipping?
A) Static
B) Sliding
C) Rolling
D) Fluid
✅ Correct Answer: A) Static
Explanation:
- A) ✔ Grip between tyre and road = static friction.
Q93. What will happen if there is no friction?
A) We can walk easily
B) Vehicles will stop
C) No motion possible
D) Nothing can move in control
✅ Correct Answer: D) Nothing can move in control
Explanation:
- D) ✔ Without friction, motion cannot be controlled.
Q94. Which factor increases friction in machines?
A) Lubrication
B) Polishing
C) Rust formation
D) Ball bearings
✅ Correct Answer: C) Rust formation
Explanation:
- C) ✔ Rust increases surface roughness.
Q95. Which of these uses friction to produce fire?
A) Gas stove
B) Matchstick
C) Electric heater
D) Candle
✅ Correct Answer: B) Matchstick
Explanation:
- B) ✔ Rubbing match → frictional heat → fire.
Q96. Which of these is a way to reduce air resistance in vehicles?
A) Make them heavier
B) Make them streamlined
C) Use rough paint
D) Add more tyres
✅ Correct Answer: B) Make them streamlined
Explanation:
- B) ✔ Streamlining reduces drag.
Q97. Why does sliding friction produce more heat than rolling friction?
A) Larger area of contact
B) More interlocking of irregularities
C) Less pressure applied
D) More lubrication
✅ Correct Answer: B) More interlocking of irregularities
Explanation:
- B) ✔ Sliding = more rubbing → more heat.
Q98. Which friction acts when a book is kept on a sloping table but does not slide down?
A) Rolling
B) Sliding
C) Static
D) Fluid
✅ Correct Answer: C) Static
Explanation:
- C) ✔ Static friction balances component of gravity.
Q99. Why is it difficult to push a heavy box on the floor?
A) Due to less friction
B) Due to static friction
C) Due to rolling friction
D) Due to buoyant force
✅ Correct Answer: B) Due to static friction
Explanation:
- B) ✔ At rest → static friction resists motion.
Q100. Why is friction called a necessary evil?
A) Only harmful
B) Only useful
C) Both useful and harmful
D) Neither useful nor harmful
✅ Correct Answer: C) Both useful and harmful
Explanation:
- C) ✔ Helps in walking, writing, etc. but causes wear and energy loss.
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