Question

a body of mass which is rest sudden its break and divided by two parts first M/4 and second M/4 and the first and both are perpendicular 3 M per second and the second is 4 metre per second what is the velocity of the third part?

Answer 1

Masses of fragments:  1/5 * 1kg,   1/5* 1kg,   3/5 * 1kg 

       ie., 0.2 kg,  0.2 kg, 0.6 kg

Linear momentum of theirs:

        0.2 * 30 m/s = 6 kg-m/s,  6 kg-m/s,  0.6 * v  kg-m/s

The vector sum of the first two :   6√2 kg-m/s   as they two linear momenta are perpendicular. This will be in North East direction, if the two pieces fly off in North and East directions respectively.

  So linear momentum of the large piece is in the direction of South West direction as Linear momentum of all three pieces is 0 (as before explosion).

  Velocity of the third piece = 6√2 kg-m/s / 0.6 kg = 10√2 m/s

          in South West dir.