Question

'n' number of balls each having mass 'm' and velocity 'u' hit a wall elastically and normally in 2 seconds. The force exerted by them on the wall is ______.

Options

• num

• `1/2`num

• - num

• `-1/2`num

Answer 1

'n' number of balls each having mass 'm' and velocity 'u' hit a wall elastically and normally in 2 seconds. The force exerted by them on the wall is num.

Explanation:

Change in momentum = nmu - (-mu) = 2nmu

Rate of change of momentum = `(2"nmu")/2="num"`