A mass of 1 kg is thrown up with a velocity of 100 m/s. After 5 seconds. It explodes into two parts. One parts of mass 400 g comes down with a velocity 25 m/s Calaculate the velocity of other parts:

Options

A. `40 m/s downwards`
B. `40 m/s upwards`
C. `100 m/s upwards`
D. `60 m/s upwards`

Answer

`(3)`

Explanation

Velocity of 1 kg mass after 5 s
`v = u -gt = 100 - 10 xx 5 = 50 ms^(-1)`
By conservation of momentum,
` 1xx 50 = 0.4 xx(-25) + 0.6 xx v.`
` v. = (60)/(0.6) = 100 ms^(-1), upwards`.