Question

A cue ball has a mass of 0.5 kg. During a game of pool, the cue ball is struck and now has a velocity of 3 . When it strikes a solid ball with a mass of 0.5 kg, the cue ball comes to a complete stop. What is the new velocity of the solid ball? Round your answer to the nearest whole number.

Answer 1

Answer: 3 m/s

Explanation:

We can solve the problem by using the law of conservation of momentum: during the collision between the two balls, the total momentum of the system before the collision and after the collision must be conserved:

$p_i = p_f$

The total momentum before the collision is given only by the cue ball, since the solid ball is initially at rest, therefore

$p_i = m_c u_c = (0.5 kg)(3 m/s)=1.5 kg m/s$

So, the final total momentum will also be

$p_f = 1.5 kg m/s$

And the total momentum after the collision is given only by the solid ball, since the cue ball is now at rest, therefore:

$p_f = m_s v_s$

from which we find the velocity of the solid ball

$v_s = \frac{p_f}{m_s}=\frac{1.5 kg m/s}{0.5 kg}=3 m/s$

Answer 2

3, just did the assignment