When a body is moving in a uniform circular motion, the work done by the centripetal force is zero because: MCQ with Answer and Explanation

When a body is moving in a uniform circular motion, the work done by the centripetal force is zero because:
A. The force is balanced by an outward centrifugal force.
B. The body has no kinetic energy.
C. The force is always perpendicular to the instantaneous displacement.
D. The force is extremely weak.
Answer: Option C
Solution (By JKSSB Mock Tests)
Work done is given by W = F * d * cos(theta). In uniform circular motion, the centripetal force is always directed strictly towards the center of the circle, while the instantaneous displacement (velocity vector) is tangential to the circle. The angle (theta) between them is exactly 90 degrees. Since cos(90) = 0, the work done by the centripetal force is always zero.

Discuss this Question (0)

No comments yet. Be the first to start the discussion!

Practice More Physics Questions

Question #1
Doppler effect for sound depends on:
A. Medium motion only
B. Observer motion only
C. Relative motion between source and observer
D. Source motion only

Correct Answer: Option C


Explanation:
Apparent frequency change depends on relative velocity between source and observer with respect to medium. Both motions contribute: f' = f(v±v_o)/(v∓v_s). Memory tip: 'Approaching ⇒ higher pitch; receding ⇒ lower pitch'. Conceptual question testing Doppler effect fundamentals, frequently examined in competitive exams.

This question belongs to: Science Physics
Question #2
Wire stretched to double length (volume constant). New resistance:
A. R
B. 4R
C. 2R
D. R/2

Correct Answer: Option B


Explanation:
Volume constant: A' = A/2 when L' = 2L. R' = ρ(2L)/(A/2) = 4ρL/A = 4R. Memory tip: 'Stretch wire: R ∝ L² when volume fixed'. Resistance proportionality frequently tested in competitive exams.

This question belongs to: Science Physics
Question #3
The centre of mass of a two-particle system lies on the line joining them, closer to
A. Depends on velocity
B. Lighter particle
C. Heavier particle
D. Midpoint always

Correct Answer: Option C


Explanation:
r_cm = (m1 r1 + m2 r2)/(m1+m2). Closer to heavier mass.

This question belongs to: Science Physics