Uniform Circular Motion & Centripetal Acceleration — IISER Physics MCQs with Solutions
Free IISER 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. Linear momentum
B. Acceleration (as a vector)
C. Velocity
D. Speed (and kinetic energy) ✓ Correct
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. mv²/r × 2πr
C. Zero ✓ Correct
D. Negative
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. 18 m/s²
B. 2 m/s²
C. 6 m/s²
D. 12 m/s² ✓ Correct
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. ≈ 20 m/s²
D. ≈ 40 m/s² ✓ Correct
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. 2 times
B. Unchanged
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. 1 : 4
B. 1 : 2 ✓ Correct
C. 1 : 1
D. 2 : 1
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 · hard · theory
In UCM, the average acceleration over one COMPLETE revolution is:
A. Undefined
B. Zero, although the instantaneous acceleration is never zero ✓ Correct
C. v²/r along the tangent
D. v²/r towards the centre
Solution: Δv⃗ = 0 over a full cycle ⇒ average acceleration = 0; instantaneous a = v²/r ≠ 0 throughout — a classic distinction.
Q8 — Uniform Circular Motion & Centripetal Acceleration · hard · numerical
A particle in UCM (radius r, speed v) sweeps a quarter circle. The magnitude of its change in velocity is:
A. Zero
B. v
C. v√2 ✓ Correct
D. 2v
Solution: Velocities before/after are ⊥ with equal magnitude: |Δv⃗| = √(v² + v²) = v√2. Trap: speed change is zero, but velocity change is not.