Question

n a ballistics demonstration a police officer fires a bullet of mass 40.0 g with speed 200 m/s on a soft plywood of thickness 4.00 cm. The bullet emerges with only 25% of its initial kinetic energy. The emergent speed of the bullet will be​

Answer 1

Answer:

In a ballistic demonstration, a police officer fires a bullet of mass 50 g with speed of 200ms−1 on soft plywood of thickness 2 cm. The bullet emerges with only 10 % of its initial kinetic energy.

Answer 2

Answer:

Mass of bullet m=40g=0.04kg

initial velocity of bullet =u=200m/s

initial energy of the bullet,  = 1/2 mu2

The bullet emerges with only 25% of its K.E.

let the final velocity with which it emerges to be v

So, final K.E is  1/2mv2 = 25/100 of initial kinetic energy

v2 = 1/4 × 800 × 2 ×÷m

so final v come s out to be 100