A body of mass `2kg` moving with a velocity of `6 m//s` strikes inelastically another body of same mass at rest. The amount of heat evolved during collision is

Options

A. `36J`
B. `18 J`
C. `9 J`
D. `3J`

Answer

B

Explanation

Common velocity, `V=(m_(1)upsilon_(1)+m_(2)upsilon_(2))/(m_(1)+m_(2))`
`=(2xx6+2xx0)/(2+2)=3 m//s`
Initial kinetic energy `(E_(1))=(1)/(2)m_(1)upsilon_(1)^(2)+(1)/(2)m_(2)upsilon_(2)^(2)`
`=(1)/(2)xx2xx6^(2)=36J`
Final kinetic energy `(E_(2))`
`=(1)/(2)(m_(1)+m_(2))V^(2)=(1)/(2)(2+2)3^(2)=18J`
The amount of heat evolved ` =E_(1)-E_(2)`
`=36-18=18J`