Answer
given,
mass of the rock ( m ) = 0.21 Kg
mass of hammer ( M ) = 0.55 Kg
initial speed of the hammer ( u ) = 5.2 m/s
final speed of the rock = ?
using energy of conservation
[tex]Mu = M v + m v'[/tex].....(1)
In elastic collision Kinetic energy is equal to final energy
[tex]\dfrac{1}{2}Mu^2 = \dfrac{1}{2}Mv^2 + \dfrac{1}{2}Mv'^2[/tex]....(2)
on solving both the equation for velocity of hammer
[tex]v' = \dfrac{M-m}{M+m}u[/tex]
[tex]v' = \dfrac{0.55-0.21}{0.55+0.21}\times 5.2[/tex]
v' = 2.33 m/s
velocity of the rock
[tex]v = \dfrac{2M}{M+m}v'[/tex]
[tex]v = \dfrac{2\times 0.55}{0.55 + 0.21}\times 2.33[/tex]
v = 3.37 m/s
