Question

Example 6.9 A body (P) of mass 5 kg moving with a velocity of 30 ms- collides with another body, Q, moving in opposite direction with a velocity of 20 ms. If both bodies now move in the direction of P at a velocity of 10 ms-l, calculate the mass of Q,.​

Answer 1

Let m be the mass of Q. By conservation of momentum,

(5 kg) (30 m/s) + m (-20 m/s) = (5 kg) (10 m/s) + m (10 m/s)

Solve for m :

600 kg•m/s - (20 m/s) m = (5 kg + m) (10 m/s)

60 kg - 2m = 5 kg + m

55 kg = 3m

m = 55/3 kg ≈ 18.333 kg