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Question
A ball of mass 0.50 kg moving at a speed of 5.0 m/s collides with another ball of mass 1.0 kg. After the collision the balls stick together and remain motionless. What was the velocity of the 1.0 kg block before the collision?
Solution
It is given that:
Speed of the ball, v1 = 5.0 m/s
Mass of the ball, m1 = 0.5 kg
Mass of another ball, m2 = 1 kg
Let the velocity of this ball be v2 m/s.
On applying the law of conservation of momentum, we get:
\[m_1 v_1 + m_2 v_2 = 0\]
\[0 . 5 \times 5 + 1 \times v_2 = 0\]
\[ \Rightarrow v_2 = - 2 . 5 \text{ m/s }\]
Hence, the velocity of second ball is 2.5 m/s, opposite to the direction of motion of the first ball.
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