A student whirls a stone tied to a string of length in a horizontal circle

PHYSICS · Single correct · CBSE · Physics · Motion in a Plane · Motion in a Plane

Problem

A student whirls a stone tied to a string of length

0.5\,\text{m}

in a horizontal circle, completing 20 revolutions in

10\,\text{s}

at constant speed. Which option gives the stone’s speed and correctly states whether the stone is accelerating? (a)

12.56\,\text{m/s}

; acceleration is zero because distance from the centre is fixed (b)

6.28\,\text{m/s}

; acceleration is not zero because velocity changes direction (c)

3.14\,\text{m/s}

; acceleration is zero because speed is constant (d)

6.28\,\text{m/s}

; acceleration is zero because the period is constant