Department of Pre-University Education, KarnatakaPUC Karnataka Science Class 11

# A Ball is Whirled in a Circle by Attaching It to a Fixed Point with a String. is There an Angular Rotation of the Ball About Its Centre? - Physics

Short Note
Sum

A ball is whirled in a circle by attaching it to a fixed point with a string. Is there an angular rotation of the ball about its centre? If yes, is this angular velocity equal to the angular velocity of the ball about the fixed point?

#### Solution

Yes, there is an angular rotation of the ball about its centre.

Yes, angular velocity of the ball about its centre is same as the angular velocity of the ball about the fixed point.

Explanation:-

Let the time period of angular rotation of the ball be T.
Therefore, we get

Angular velocity of the ball about the fixed point = $\frac{2\pi}{T}$

After one revolution about the fixed centre is completed, the ball has come back to its original position. In this case, the  point at which the ball meets with the string is again visible after one revolution. This means that it has undertaken one complete rotation about its centre.

The ball has taken one complete rotation about its centre. Therefore, we have

Angular displacement of the ball = $2\pi$

Time period = T

So, angular velocity is again $\frac{2\pi}{T}.$

Thus, in both the cases, angular velocities are the same.

Is there an error in this question or solution?

#### APPEARS IN

HC Verma Class 11, 12 Concepts of Physics 1
Chapter 10 Rotational Mechanics
Short Answers | Q 4 | Page 192