a bullet of mass 50g is moving with a velocity of 500m/s. it penetrates 10cm into a still target and comes to rest. calculate a. the kinetic energy possessed by the bullet b. the average retarding force offered by the target.

Here, m = 50 g = 50 × 10^-3 kg, u = 500 ms^-1, s = 10 cm, v = 0, KE = ?, F = ? 

(i) KE = 1/2mv² = 1/2×50 × 10^-3 × (500)2 = 6250 J. 

(ii) Using v² – u² = 2aS, we get 

a = {v² – u²}/{2aS} = {02 – (500)2}/{2 × 10 ×10^-2} 

= – 1250000ms^-2.

Therefore, retarding force, F = ma = 50 × 10^-3 × 1250000 = 62500 N.