Question

A 30kg bullet strikes a tree trunk of diameter 40cm at 200ms and leaves it from the opposite side at 100ms find the kinetic energy of the bullet just before it strikes the tree

Answer 1

Before it strikes the tree:

KE = 1/2 m v^2 = 1/2 * 30 kg * (200 m/s)^2

This KE would be 6.0E5 Joules

30 kg would about 66 lbs - obviously too heavy

You might consider 30 mg = .03 kg (still quite heavy)

KE = 1/2 * .03 kg * 40000 m.s^2 = 600 J more realistic