Question

A motorcyclist rides in a vertical circle in a hollow sphere of radius $5m$. Find the minimum speed with which the motorcyclist should move, so that he does not lose contact with the sphere even at the highest point. ($g=9.8m/s^2$)

Answer 1

Motorcyclist is basically looping the vertical loop and hence tension at the top will be zero.

$\therefore v_{bottom}=\sqrt{rg}=\sqrt{5\times 9.8}=7\frac{m}{s}$