A collision can change both carts’ motions. Two carts can bounce apart or stick together. If they stick, they move at the same speed afterward. Total momentum is shared across the pair, not kept separately by each cart. For carts that stick, multiply the moving cart’s mass by its starting speed, then divide by the combined mass to find the shared speed.
Forces, motion and energy · Discover & try
What stays the same when two carts collide?
Reading level 1 of 5 · EarlyChange
Word help
Elastic collision
An ideal collision preserving total kinetic energy as well as momentum.
Sticking collision
A collision after which objects share one velocity.
System
The chosen collection of objects whose total quantities are compared.
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See how it works
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One-dimensional ideal collision; no external impulse and no claim about material damage.
What to look for
- After contact, the incoming cart reverses and the target moves right.
- After contact, both share one velocity: 1.2 m/s right.
Explain what you noticed
A different 1 kg cart moving at 6 m/s sticks to a stationary 2 kg cart. What shared speed follows in the isolated model?
Keep this idea: Total momentum is conserved for an isolated system; kinetic energy is conserved only in the ideal elastic case.
Follow the sources
- OpenStax, Rice University — Conservation of Momentum
- OpenStax, Rice University — Elastic and Inelastic Collisions
Source material checked 2026-10-29. Explanations and activities by Nepedia. Source links do not imply endorsement.
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