An explosion blows a rock into three pieces. Two pieces go off at right angles to each other. One of these two pieces of mass 1 kg moves with 12 m//s and other of mass 2 kg moves with 8 m/s. If the velocity of the third piece is 40 m//s, then its mass is:

Options

A. 5 kg
B. 0.5 kg
C. 0.25 kg
D. 1 kg

Answer

b

Explanation

`vecp_(1)=m_(1)upsilon_(1)=1xx12=12kgm//s`
`vecp_(2)=m_(2)upsilon_(2)=2xx8=16kgms^(-1)`
Since total momentum is zero.:.`vecp_(3)`must be equal and opposite to resultant of `vecp_(1)`and`vecp_(2)`
`:.m_(3)upsilon_(3)=sqrt(p_(1)^(2)+p_(2)^(2))=20impliesm_(3)=(20)/(40)=(1)/(2)kg`
` (##MOD_RPA_OBJ_PHY_C04_A_E01_008_S01.png" width="80%">Thus correct choice is (b).