# A ball with a mass of 2 kg is rolling at 12 m/s and elastically collides with a resting ball with a mass of 1 kg. What are the post-collision velocities of the balls?

Feb 8, 2016

${v}_{1} = 4 \frac{m}{\sec}$
${v}_{2} = 16 \frac{m}{\sec}$

#### Explanation:

$2 \cdot 12 + 1 \cdot 0 = 2 \cdot {v}_{1} + 1 \cdot {v}_{2}$
$24 = 2 \cdot {v}_{1} + {v}_{2}$
$12 + {v}_{1} = {v}_{2}$
$24 = 2 \cdot {v}_{1} + 12 + {v}_{1}$
$24 - 12 = 3 \cdot v 1$
$12 = 3 \cdot {v}_{1}$
${v}_{1} = 4 \frac{m}{\sec}$
$12 + 4 = {v}_{2}$
${v}_{2} = 16 \frac{m}{\sec}$