Question

In travelling the 70 cm along a rifle barrel, a bullet uniformly accelerates from rest to a velocity of 210 m s-1. Find the acceleration involved and the time taken for which the bullet is in the barrel.

Answer 1

The acceleration of a bullet

$$a=\frac{v_f^2-v_i^2}{2d}=\frac{210^2-0^2}{2\times 0.70}=315\:\rm m/s^2$$

The time of motion through the barrel

$$t=\frac{v_f-v_i}{a}=\frac{210-0}{315}=0.67\:\rm s$$