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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?
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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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