A body of mass `m` falls from a height `h` and collides with another body of same mass at rest. After collision, the two bodies combine and move through distance `(d)` till they come to rest. Find the work done against the resistive force.

Explanation

`m_(1)=m_(2) = m `
`v_(1) = sqrt(2gh) , v_(2) = 0 `
According to principle of conservation of momentum
`m_(1)v_(1)+m_(2)v_(2) = (m_(1)+m_(2))v`
`msqrt(2gh) +m_(2).0 = (m+m) v `
`msqrt(2gh) = 2mv `
`sqrt((gh)/(2)) = v `
Work done against resistive force ` = 1/2 (2m)v^(2)`
` = 1/2 xx 2m xx (gh)/2 =(mgh)/2 `