Question

A ball of mass m is attached to a string. It is spun around at a distance r at 2 m/s, where the tension in the string is measured to be 10 N. If the ball is then spun around at 8 m/s, what is the new tension in the spring?

Answer 1

When the ball is spun with the help of string. Then Tension in the string is exactly balanced by the centripetal force acting on the ball.

Now Radius of spinning= r

Initial Tension, T₁= 10N

Initial speed, v₁= 2m/s

Then Tension in the string, ......................(1)

Now if the speed is changed then new speed of ball, v₂= 8m/s

Let changed Tension in the string is T₂, then again we'll have

  ...............................(2)

Dividing equation 2 by 1, we'll get

Using all given values in above,

  

(ANS)