How much momentum will a dumb-bell of mass `10kg` transfer to the floor if it falls a height of `80 cm`? Take its downward acceleration to be `10 m//s^(2)`.

Explanation

`u = 0 , a = 10 m//s^(2), h = 80 cm = 0 . 8 m`
`v^(2) = u^(2) + 2ah`
`v^(2) = 0 + 2 xx 10 xx 0 . 8`
`v^(2) = 16 rArr v = 4 m// s `
Change in momentum = mv - mu
`= 10 kg xx 4 m//s " "` [` :. u = 0` ]
= 40 kg m//s
Time taken to reach the floor
`v = u + at or t = (v)/(a) " "` [`:. u = 0 `]
`rArr t = (4)/(10) = 0 . 4`
Force on the floor , F ` = m (v - u) // t = ((10 xx 4))/(0 . 4) = 100 N`