A lead bullet of mass 21 g travelling at a speed of `100m//s` comes to rest in a wooden block . If no heat is taken away by the wood , the rise in temperature of the bullet in the wood nearly is (specified heat of lead =`30 cal//kg^(@)C` )

Explanation

Kinetic energy of the bullet=heat gained by the bullet `1/2 mv^(2) = msDeltat`
`Delta t =(v^(2))/(2s) = ((100^(2)))/(2xx0.03xx4.2xx1000) = 39.68^(@)C`