Question

A bullet moving at 20m/sec.It strikes wooden plank and penetrates 4cm before coming to stop.The time taken to stop is

Answer 1

u=30m/s

s=4cm=0.04m

v=0

t=?

s=(v+u/2)×t

0.04=30+0/2×t

t=0.04/15

t=0.00267s