Question

A bomb at rest explodes onto three fragments . two fragments fly off at right angles to each other. These two fragments: the one with mass 2 kg moves with a speed of $12m{s}^{-1}$, and the other one with mass 1 kg moves with $[8m{s}^{-1}$ . The speed of the third fragment is $20m{s}^{-1}$, then calculate its mass.

Answer 1

The initial momentum is 0

Initial momentum = final momentum

Final momentum:

Resultant momentum for the two is.

Mass is constant and depends not on the direction.

12² + 9² = 225

The resultant velocity = √225 = 15m/s

Since the mass is equal we have.

Momentum = 15m

Let the velocity of the third one be v

The final momentum is = mv + 15m

0 = mv + 15m

-15m = mv

v = - 15

The velocity of the third one is :

15 m/s