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Heavy hits light object
Intermediate
The heavy object continues almost unchanged while the light flies off at about twice the speed.
The heavy body continues nearly unchanged and the light one is knocked off at about twice the heavy body's speed.
A truck hitting a ball sends it off at about 2v.
Energy is shared, but most stays with the heavy body.
In more detail
When a heavy object hits a light one at rest, the heavy object continues almost unchanged and the light one moves forward at nearly twice the heavy object's speed.
Real-world uses
- A bowling ball striking a ping-pong ball sends the ping-pong ball rapidly forward.
- Gravitational slingshots in space use an analogous exchange with massive planets.
- A bowling ball rolling into a pile of ping-pong balls keeps moving almost unchanged while the light balls fly off.
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Frequently asked questions
Why is the light object so fast?
Because it takes most of the kinetic energy from the heavy object in an elastic collision.
Does the heavy object stop?
No. It keeps moving with almost the same speed.
Does the heavy object stop?
Hardly. The heavier body keeps almost all its velocity, because it has a much larger momentum than the light body.
Related topics in Momentum & Collisions
Elastic head-on collision velocities · Equal masses collide elastically · Light hits heavy object · Energy lost in inelastic collision · Reduced mass · Collisions in two dimensions