Question

What is the velocity of a 0.03 kg bullet that has a KE of 3750 J when fired from a rifle?And construct the free-body diagrams?

Answer 1

The kinetic energy is given by

$$E_k=\frac{mv^2}{2}$$

The velocity of bullet

$$v=\sqrt{2E_k/m}=\sqrt{2*3750/0.03}=500\:\rm m/s$$

The free-body diagram is as follows