Question

A bullet of mass 50g enters a block of thickness t with speed of 500 m/s it emerges

Answer 1

Mass of bullet = m = 50g = 0.05kg

Initial velocity of bullet = u = 200 m/s

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

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

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

= ½ mv square = (10/100) x 1000

= v square = 100 x 2/0.05

= v = 63.24 m/s

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