Question

N bullets each of mass m kg are fired with a velocity $vms^{- 1}$ at the rate of n bullets per second upon a wall. The reaction offered by the wall to the bullets is given by

• A. nmv
• B. $\frac{Nmv}{n}$
• C. $n\frac{Nm}{v}$
• D. $n\frac{Nv}{m}$

Answer 1

Answer: (A)

nmv

Answer 2

Total mass of bullets = Nm, time $t = \frac{N}{n}$

Momentum of the bullets striking the wall = Nmv

Rate of change of momentum (Force) = $\frac{Nmv}{t}$= nmv.