Final answer:
The launch speed of the plastic ball is approximately 8.85 m/s.
Step-by-step explanation:
To find the launch speed of the plastic ball, we can use the principle of conservation of energy. The potential energy of the steel ball before it is dropped is converted into kinetic energy when it reaches its lowest point. This kinetic energy is then transferred to the plastic ball during the collision. We can use the equation:
1/2 mv^2 = mgh
where m is the mass of the steel ball, v is the launch speed of the plastic ball, g is the acceleration due to gravity, and h is the height the steel ball falls. Rearranging the equation:
v = √(2gh)
Substituting the given values:
v = √(2 * 9.8 m/s^2 * 4 m)
= √78.4 m/s
≈ 8.85 m/s