Question

A wrecking ball attached to the end of a long, essentially massless chain is released from rest, from a height H = 5 meters off the ground, as shown in figure 1. At the lowest point of its swing, it collides with a piece of modern sculpture. Since the sculpture is made of wet clay, it sticks to the wrecking ball. The wrecking ball has mass 200 kg. The sculpture has mass 100 kg.

As the ball swings down from its starting point, its acceleration along the direction of motion: decreases.

pic:https://gyazo.com/bfceb180acff27a13fef8e27913504ce

Why does it decrease? Include free body diagrams in explanation

Answer 1

The gravitationla force mg always acts downward but he ball can only move along a circle of radius l , where l is length of the chain.

supose at a given instant the the chain makes an angle p with the verticle.

The component of the weight that acts along the direction of motion i.e tangential to the circle is

mgsin(p)

acceleration along the direction of motion = gSin(p)

as the ball comes down p reduces and hence the acclearation decreases, at the bottom p=0 and the acceleration =0.