A smooth block loosely fits in a circular tube placed on a horizontal surface. The block moves in a uniform circular motion along the tube as shown in figure below. Which wall (inner or outer) will exert a non-zero normal contact force on the block?

Question

Philoid · Accepted Answer

In a uniform circular motion, the blocks speed remains constant but its direction changes constantly. Here, we observe

centripetal acceleration along the radius of the circular path acting inwards towards the center. So, there must be a resultant nonzero force in this direction called centripetal force acting towards center. So, here the outer wall will exert a nonzero normal force on the block in the direction of center of the tube.