Question

a bullet of mass 20g moving with a speed of 75m/s hits a fixed wooden plank and comes to rest after penetrating a distance of 5 cm.wht is the average resistive force exerted by wooden plank on bullet

Answer 1

From relation, v2 = u2 + 2aS
or, 0 = 75x75 + 2xax0.05
or, a = -5625/0.05 m/s2 = 112500 m/s2

Resistive force = 112500 x 20/100 N = 2250 N (answer)