A bob of mass m is suspended by a light string of length L It is imparted a horizontal velocity - Physics - Work Energy And Power

Question

A bob of mass m is suspended by a light string of length L It is
imparted a horizontal velocity v0at the lowest point A
such that it completes a semi- circular trajectory in the vertical
plane with the string becoming slack only on reaching the topmost
point,C Obtain an expression for
i) v0
ii)the speeds at point B and C

Ruhhi Ralhan · Accepted Answer

Hi, Here is the answer to your query Given: Mass of the bob=m, Length of the string=L, Initial velocity impart at point A=v0 The tension force will not work on the bob as the displacement will always be perpendicular to the string At point A: Total mechanical energy,

(As the potential energy is zero) … 1 The centripetal force for the circular motion will be,

At the highest point C, as the string slackens the tension becomes zero Then,

The total energy,

So at A,

(Using 1) Now, at B,

Hope, you got the answer Best wishes!!