Question
A bullet fired against a window glass pane makes a hole in it and the glass pane is not cracked. On the other hand, a stone striking the same glass pane will smash it. Explain why?
Solution
When a bullet is fired and hits the glass, the part of the glass which comes in contact with the bullet immediately has a tendency to share the large velocity of bullet. This way it makes a hole while the remaining part of the glass due to inertia of rest remains at rest. Hence, the glass pane is not smashed.
When a stone with low velocity strikes the glass, the surrounding part of the glass takes time to share the velocity of the stone. Thus the glass is smashed.
