Astone tied to the end of a string is whirled around in
avertical circle of radius r. find the critical speed below
whichthe spring would become slack at the highest point.

Explanation:

radius of circle = R

Let T be the tension in the string.

At highest point A, the tension is equal to or more than zero, so that it completes the vertical circle. tension and weight is balanced by the centripetal force.

According to diagram,

T ≥ 0

So,

Where, v be the speed at the highest point, which is called the critical speed.

Thus, the critical speed at the highest point to complete the vertical circle is  .

true is the correct answer

hope i