Question

in a ballistic demonstration a police officer fires a bullet of mass 50.0 g with speed 200 m/s on soft plywood of thickness 2.00 cm the bullet emerges with only 10% of its initial kinetic energy what is emergent speed of the bullet

Answer 1

Answer:

Mass of bullet m=50g=0.05kg

initial velocity of bullet =u=200m/s

initial energy of the bullet,

2

1

mu

2

\frac{1}{2}\left( {0.05} \right)\left( {200\,square} \right) = 1000J$$

The bullet emerges with only 10% of its K.E.

let the final velocity with which it emerges to be v

So, final K.E is

2

1

mv

2

10% of

2

1

mu

2

2

1

mv

2

(

100

10

)×1000

=v

2

=100×

0.05

2

=v=63.24m/s

Hence,

option (C)$ is correct answer.