An explosion blows a rock into three parts. Two parts go off at right angles to each other . These two are `1 kg` first part moving with a velocity of `12 ms^(-1) and 2 kg` second part moving with a velocity of `8 ms^(-1)`. If the third part flies off with a velocity of `4 ms^(-1)`. Its mass would be

Options

A. 3 kg
B. 5 kg
C. 7 kg
D. 17 kg

Answer

B

Explanation

`vec(P_(1))+vec(P_(2))+vec(P_(3))=0`
`|vec(P_(3))|=|vec(P_(1))+vec(P_(2))|`
`mxx4=sqrt(P_(1)^(2)+P_(2)^(2))`
`=sqrt(12^(2)+16^(2))`
`m=5kg `