A bullet of mass `m` moving with velocity `v` strikes a block of mass `M` at rest and gets embedded into it. The kinetic energy of the composite block will be

Options

A. `1/2mv^2xx(m)/((m+M))`
B. `1/2mv^2xx(M)/((m+M))`
C. `1/2mv^2xx((m+M))/(M)`
D. `1/2mv^2xx(m)/((m+M))`

Answer

A

Explanation

`mv = (m+M)v.impliesv. = ((m)/(m+M))v`
K.E. of composite block
K.E. `=1/2 (m+M) [(m^2)/((m+M)^2)]v^2`
`=1/2 (m^2v^2)/((m+M))=1/2 mv^2 (m/(m+M))`