Question

A bullet leaves a rifle with a muzzle velocity of 400 m/s. While accelerating through the

barrel of the rifle, the bullet moves a distance of 0.840 m. Determine the acceleration of the

bullet.

Answer 1

The question states that 0.840 m is the distance travelled within the barrel. Therefore u = 0 m/s, v= 521 m/s. 
This means that a = (v^2 - u^2)/2s. 
This is a reformat of v^2 = u^2 + 2as 
a = (521^2)/(2 x 0.840) 
a = 161.57 m/s^2