Question

I
the bullet emerges with only 10% of its initial kinectic energy pls see image for whole question

Answer 1

Here,

Mass of bullet, m = 50 g = 0.05 kg

Initial velocity of bullet, u = 200 m/s

Initial energy of the bullet, ½ mu^2 = ½ (0.05)(200^2) = 1000 J

The bullet emerges with only 10% of its KE. Let the final velocity with which it emerges be v.

So, final KE is, ½ mv^2 = 10% of ½ mu^2

=> ½ mv^2 = (10/100) × 1000

=> v^2 = 100 × 2/0.05

=> v = 63.24 m/s

Answer 2

changs in kinetic energy equals work done by the bullet to pass through plywood

given condition states

ke equals kinetic energy at state 1 and 2

ke2=10%ke1
v2=(1/√10)v1

emergent velocity v2= (1/√10)200

v2=63.25 m/s