Question

A ball of mass $1kg$, moving with a velocity of $0.4m/s$ collides with another stationary ball. After the collision, the first ball moves with a velocity of $0.3m/s$ in a direction making an angle of $90^{o}$ with its initial direction. The momentum of second ball after collision will be (in kg-m/s)

• A. 0.1
• B. 0.3
• C. 0.5
• D. 0.7

Answer 1

Answer: (C)

0.5

Answer 2

Let second ball moves with momentum P making an angle θ from the horizontal (as shown in the figure).

By the conservation of horizontal momentum

$1 \times 0.4 = P\cos\theta$ ......(i)

By the conservation of vertical momentum 0.3 =$P\sin\theta$......(ii)

From (i) and (ii) we get P = 0.5 kg-m/s