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Light hits heavy object
Intermediate
The light object rebounds with nearly the same speed.
A light body rebounds with almost its original speed, and the heavy target barely moves, like a ball bouncing off a wall.
Tennis ball hitting a wall at 10 m/s returns at nearly 10 m/s.
The momentum change belongs to the heavy object, but its speed change is tiny.
In more detail
When a light object hits a heavy one that is at rest, the light object bounces back with nearly its original speed, and the heavy object barely moves.
Real-world uses
- A tennis ball bounced off a wall rebounds almost at full speed.
- A table tennis ball bounced off a heavy stone surface rebounds quickly.
- A ping-pong ball hitting a bowling ball rebounds with nearly its original speed, while the bowling ball barely moves.
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Frequently asked questions
Why does the light object rebound?
Because the heavy object acts almost like a fixed wall, reflecting the ball.
What happens to the heavy object's speed?
It moves only slightly, since its mass is much larger.
Why does the light ball bounce so hard?
The light ball reverses its velocity, a change of about twice its approach speed, because the heavy object acts almost like a fixed wall.
Related topics in Momentum & Collisions
Coefficient of restitution · Elastic head-on collision velocities · Equal masses collide elastically · Heavy hits light object · Energy lost in inelastic collision · Reduced mass