Question

A disc of mass 10 gm is kept floating horizontally by throwing 10 marbles/sec against it from below. If the mass of each marble is 5 g; calculate the velocity with which the marbles are striking the disc. Assume that the marbles strike the disc normally and rebound downward with the same speed.​

Answer 1

The mass of plate is M = 100 g = 0.1 kg

The mass of bullet is m = 5 g = 0.005 kg

The bullets are fired at a rate of 10 bullets per second.

Let v be the speed of each bullet.

After colliding with the plate, they rebound with same speed.

Thus, rate of change in momentum of the bullets, that is, the force exerted by bullets is

2 v × 0.005 × 10

This balances the weight of the plate.

2 v × 0.005 × 10 = 0.1 × 9.8

v = 9.8 m/s

Answer 2

Explanation:

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