A stone tied to a string is whirled in a circle. The work done by tension in string is MCQ with Answer and Explanation

A stone tied to a string is whirled in a circle. The work done by tension in string is
A. Negative
B. Zero
C. Variable
D. Positive
Answer: Option B
Solution (By JKExamLibrary)
Tension is towards centre, displacement is tangential (velocity). Force perpendicular to displacement, cos90°=0, work zero. Centripetal force does no work, doesn't change speed.

This question belongs to: Science Physics

Discuss this Question (0)

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

Practice More Physics Questions

Question #1 Report Error
Which of the following materials is used as a fuse wire?
A. Tin-lead alloy
B. Silver
C. Copper
D. Aluminium

Correct Answer: Option A


Explanation:
Fuse wire made of alloy of tin and lead (or copper with low melting point). It has low melting point and high resistance. Copper has high melting point, not suitable for fuse. Silver expensive. Aluminium not typical.

This question belongs to: Science Physics
Question #2 Report Error
The position-time graph of a particle is a parabola opening upwards. This indicates that the particle has:
A. Constant velocity
B. Decreasing acceleration
C. Constant acceleration
D. Increasing acceleration

Correct Answer: Option C


Explanation:
Position-time graph as parabola: x = x₀ + ut + ½at². This quadratic form indicates constant acceleration 'a'. If acceleration were changing, the graph would be cubic or higher order. Constant velocity would produce a straight line (linear graph). Upward opening parabola implies positive acceleration. Graph interpretation skill is essential: slope of x-t graph = velocity; curvature indicates acceleration. Memory tip: Parabolic x-t graph ⇔ constant acceleration; linear x-t graph ⇔ constant velocity. Competitive exams frequently test graph-concept correlations.

This question belongs to: Science Physics
Question #3 Report Error
Lens power P = -4 D. Focal length and type:
A. 25 cm, concave
B. 25 cm, convex
C. 40 cm, concave
D. 40 cm, convex

Correct Answer: Option A


Explanation:
P = 1/f(m) ⇒ f = 1/P = 1/(-4) = -0.25 m = -25 cm. Negative focal length indicates diverging (concave) lens. Memory aid: 'Negative power = concave lens; f(cm) = 100/P(D)'. Direct lens power application frequently tested in competitive exams with sign convention awareness.

This question belongs to: Science Physics