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` )

Options

A. `25^(@)C`
B. `28^(@)C`
C. `33^(@)C`
D. `39^(@)C`

Answer

D

Explanation

Heat produced, `Q = K.E`
`msDeltat=(1)/(2)xxmxxV^(2)`
`implies 30xx Deltat=(1)/(2)xx(100)^(2)xx(1)/(4.2)`
`therefore Deltat=39.683^(@)C`