Centripetal & Centrifugal Force — JEE Main Physics MCQs with Solutions
Free JEE Main Physics Centripetal & Centrifugal Force 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 — Centripetal & Centrifugal Force · easy · theory
Centrifugal force is:
A. Always present in the ground frame
B. A real reaction to the centripetal force
C. The force that keeps a body in a circle
D. A pseudo force that appears only in the rotating (non-inertial) frame ✓ Correct
Solution: It exists only for observers in the rotating frame (magnitude mω²r, outward). In the inertial frame only the real centripetal force acts. Trap: it is NOT the Newton's-third-law pair of the centripetal force.
Q2 — Centripetal & Centrifugal Force · medium · theory
A stone whirled on a string breaks free. In the ground frame, immediately afterwards it moves:
A. Along the tangent to the circle at the point of release ✓ Correct
B. Radially outward
C. In a spiral
D. Radially inward
Solution: With no centripetal force, inertia carries it along its instantaneous velocity — the tangent. "Flying outward" is the rotating-frame illusion.
Q3 — Centripetal & Centrifugal Force · easy · numerical
A 0.5 kg stone moves in a horizontal circle of radius 2 m at 6 m/s. The centripetal force is:
A. 9 N ✓ Correct
B. 36 N
C. 18 N
D. 3 N
Solution: F = mv²/r = 0.5×36/2 = 9 N.
Q4 — Centripetal & Centrifugal Force · medium · numerical
A 2 kg body is whirled at 5 rad/s in a circle of radius 0.4 m. In the rotating frame, the centrifugal force experienced is:
A. 20 N outward ✓ Correct
B. 50 N outward
C. 20 N inward
D. 4 N outward
Solution: F = mω²r = 2×25×0.4 = 20 N, directed radially outward in the rotating frame.
Q5 — Centripetal & Centrifugal Force · hard · numerical
A string of breaking tension 100 N whirls a 1 kg stone in a horizontal circle of radius 1 m. Neglecting gravity, the maximum angular speed before the string snaps is:
A. 5 rad/s
B. 100 rad/s
C. 10 rad/s ✓ Correct
D. 20 rad/s
Solution: T = mω²r ⇒ ω_max = √(100/(1×1)) = 10 rad/s.
Q6 — Centripetal & Centrifugal Force · medium · numerical
The centripetal force on a body in UCM is F. If its speed is tripled at the same radius, the required force becomes:
A. 3F
B. 6F
C. 9F ✓ Correct
D. F/3
Solution: F = mv²/r ∝ v² ⇒ ×9.
Q7 — Centripetal & Centrifugal Force · hard · numerical
A ball of mass 0.5 kg on a string moves in a HORIZONTAL circle of radius 1 m with speed 4 m/s; the string makes angle θ with the vertical (conical setup). The tension in the string is:
A. 5 N
B. 8 N
C. √(m²g² + (mv²/r)²) = √(25 + 64) ≈ 9.4 N ✓ Correct
D. 13 N
Solution: T sinθ = mv²/r = 8 N and T cosθ = mg = 5 N ⇒ T = √(8² + 5²) = √89 ≈ 9.4 N.
Q8 — Centripetal & Centrifugal Force · medium · numerical
A 1 kg block on a smooth table moves in a circle of radius 0.5 m; the string passes through a hole at the centre of the table and supports a hanging 2 kg mass in equilibrium. The block's speed is:
A. 2 m/s
B. √10 ≈ 3.2 m/s ✓ Correct
C. 10 m/s
D. √20 m/s
Solution: Tension = weight of the hanging mass = 20 N = mv²/r ⇒ v² = 20×0.5/1 = 10 ⇒ v = √10 m/s.