Uniform Circular Motion & Centripetal Acceleration — JEE Main Physics MCQs with Solutions
Free JEE Main Physics Uniform Circular Motion & Centripetal Acceleration MCQs with step-by-step solutions (8 questions). Part of Circular Motion. Practise online on Prepizo — no login needed.
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Questions with solutions
Q1 — Uniform Circular Motion & Centripetal Acceleration · easy · theory
In uniform circular motion, which quantity remains constant?
A. Speed (and kinetic energy) ✓ Correct
B. Velocity
C. Linear momentum
D. Acceleration (as a vector)
Solution: Speed is fixed but the DIRECTIONS of v⃗, a⃗ and p⃗ rotate continuously — none of those vectors is constant.
Q2 — Uniform Circular Motion & Centripetal Acceleration · medium · theory
In UCM, the work done by the centripetal force in one full revolution is:
A. 2πr × F
B. Negative
C. mv²/r × 2πr
D. Zero ✓ Correct
Solution: F ⊥ v at every instant, so no work is ever done; KE stays constant, consistent with constant speed.
Q3 — Uniform Circular Motion & Centripetal Acceleration · easy · numerical
A particle moves at 6 m/s on a circle of radius 3 m. Its centripetal acceleration is:
A. 12 m/s² ✓ Correct
B. 6 m/s²
C. 18 m/s²
D. 2 m/s²
Solution: a_c = v²/r = 36/3 = 12 m/s².
Q4 — Uniform Circular Motion & Centripetal Acceleration · medium · numerical
A satellite completes a circular orbit of radius 4 m (model) in 2 s. Its centripetal acceleration is (π² ≈ 10):
A. ≈ 4 m/s²
B. ≈ 80 m/s²
C. ≈ 40 m/s² ✓ Correct
D. ≈ 20 m/s²
Solution: ω = 2π/T = π rad/s; a_c = ω²r = π²×4 ≈ 40 m/s².
Q5 — Uniform Circular Motion & Centripetal Acceleration · hard · numerical
If the speed of a particle in UCM doubles and the radius is halved, the centripetal acceleration becomes:
A. Unchanged
B. 2 times
C. 8 times ✓ Correct
D. 4 times
Solution: a = v²/r → (2v)²/(r/2) = 8v²/r — an 8-fold increase.
Q6 — Uniform Circular Motion & Centripetal Acceleration · medium · numerical
Two particles ride at radii r and 2r on the same rotating disc. The ratio of their centripetal accelerations (inner : outer) is:
A. 2 : 1
B. 1 : 2 ✓ Correct
C. 1 : 1
D. 1 : 4
Solution: Same ω on a rigid disc ⇒ a = ω²r ∝ r ⇒ ratio 1:2. Trap: using a = v²/r with the same v is wrong here.
Q7 — Uniform Circular Motion & Centripetal Acceleration · medium · numerical
A particle in UCM of radius 0.5 m has position angle θ = 4t (rad). The magnitude of its acceleration is:
A. 4 m/s²
B. 16 m/s²
C. 8 m/s² ✓ Correct
D. 2 m/s²
Solution: ω = dθ/dt = 4 rad/s (uniform); a = ω²r = 16×0.5 = 8 m/s².
Q8 — Uniform Circular Motion & Centripetal Acceleration · hard · numerical
A particle moves uniformly on a circle, taking time T per revolution. The magnitude of its average velocity over HALF a revolution (radius r) is:
A. πr/T
B. Zero
C. 4r/T ✓ Correct
D. 2πr/T
Solution: Displacement over half rev = 2r (diameter); time = T/2 ⇒ |v_avg| = 2r/(T/2) = 4r/T. Trap: average speed is πr/(T/2) = 2πr/T instead.