Question

When the batsman hits the fast ball what happens to the kinetic energy transferred to the bat?

Answer 1

kinetic energy converted into sound and potential energy etc.

Answer 2

According to the law of conservation of energy ,"  Energy is neither created nor destroyed , its transformed from one of energy into another."

So here, when  the batsman hits the fast ball , the kinetic energy transferred to the bat gets converted into sound energy, heat energy and as potential energy .