Question
Wed December 28, 2011 By:

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.

Expert Reply
Thu December 29, 2011

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. 

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