Question

A bullet of mass 50 grams moving with a velocity 400 m per second strikes wall and goes out from the other side with a velocity hundred metre per second calculate the work done passing through the wall

Answer 1

work = (1/2)*(400^2-100^2)*0.05
= (150000/2)*0.05
= 75000*0.05
= 3750 J.

thanks for asking.

Answer 2

We can easily answer this question by the conservation of energy,

Kinetic energy of the bullet before it hits the wall - K1

Kinetic energy of the bullet after it hits the wall -    K2

Work done by the bullet passing through the wall - W

By the conservation of energy,

$K1  = W +K2$

1/2 x 50 x 10^-3 x 400^2 = W + 1/2 x 50 x 10^-3 x 100^2

W = 1/2 x 50 x 10^-3 x 300^2

W = 3750 J