Friction — Homi Bhabha Exam Physics MCQs with Solutions
Free Homi Bhabha Exam Physics Friction MCQs with step-by-step solutions (6 questions). Part of Laws of Motion & Force. Practise online on Prepizo — no login needed.
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Questions with solutions
Q1 — Friction · medium · theory
The force of friction between two surfaces always acts:
A. opposite to the direction of relative motion ✓ Correct
B. downward
C. in the direction of motion
D. perpendicular to the surface
Solution: Friction opposes (or tends to oppose) the relative motion between the surfaces in contact.
Q2 — Friction · medium · theory
Ball bearings are used in machines because:
A. rolling friction is larger than sliding friction
B. they eliminate friction completely
C. rolling friction is much smaller than sliding friction ✓ Correct
D. they increase friction
Solution: Converting sliding into rolling greatly reduces friction, since rolling friction is much smaller.
Q3 — Friction · hard · theory
For two given surfaces, which statement is correct?
A. Friction is zero once motion starts
B. Kinetic friction is greater than static friction
C. Limiting (maximum static) friction is greater than kinetic friction ✓ Correct
D. Both are always equal
Solution: It takes a larger force to start motion than to keep it going, so limiting static friction exceeds kinetic friction.
Q4 — Friction · hard · numerical
A block presses on a surface with a normal force of 50 N. If the coefficient of friction is 0.2, the frictional force is:
A. 50.2 N
B. 10 N ✓ Correct
C. 250 N
D. 2.5 N
Solution: Friction $= \mu N = 0.2 \times 50 = 10$ N.
Q5 — Friction · medium · theory
The treads (grooves) on vehicle tyres are provided to:
A. increase friction (grip) with the road ✓ Correct
B. reduce friction with the road
C. make the tyre look attractive
D. reduce the weight of the tyre
Solution: Treads increase the grip (friction) between tyre and road, improving traction and braking.
Q6 — Friction · hard · theory
Assertion (A): Friction is called a "necessary evil". Reason (R): Friction wastes energy as heat but is also needed for walking and braking.
A. Both A and R are true but R is NOT the correct explanation of A
B. Both A and R are true and R is the correct explanation of A ✓ Correct
C. A is false but R is true
D. A is true but R is false
Solution: Friction both wastes energy (evil) and is essential for walking/gripping (necessary) — R correctly explains why it is a necessary evil.