Elastic collision
The balls bounce apart. Total momentum and kinetic energy stay the same in the ideal model.
Physics Learning Tool
Momentum Conservation and Collision Simulator
Change the mass and signed velocity of two balls, choose elastic or inelastic collision, and compare total momentum before and after.
Core idea: In an isolated system, total momentum before collision equals total momentum after collision: m1v1i + m2v2i = m1v1f + m2v2f.
Collision type
Elastic keeps kinetic energy. Inelastic makes the balls stick together.
2.00 kg
Larger mass makes the blue ball bigger and changes its momentum.
4.00 m/s
Use negative values when ball 1 moves left.
2.00 kg
Try a heavy slow ball and a light fast ball.
-2.00 m/s
The sign matters because momentum is a vector.
External force check
Turn on to add an outside impulse after collision.
4.00 kg m/s
Impulse changes total momentum, so the system is no longer isolated.
Initial total p4 kg m/s
Final total p4 kg m/s
Difference0
Kinetic energyelastic
m1v1i + m2v2i = m1v1f + m2v2fThe system is isolated, so total momentum is conserved.
What to notice
- Momentum depends on both mass and velocity.
- A heavier slow ball can match a lighter fast ball.
- Negative velocity gives negative momentum, so direction changes the total.
Collision lessons
Inelastic collision
The balls stick together and move with one final velocity. Momentum is conserved, but kinetic energy decreases.
Isolated system
Momentum conservation works when no outside force gives the system an extra push or pull.
Practice keywords
Use this tool to explore Momentum Conservation and Collision, elastic collision, inelastic collision, signed velocity, impulse, and total momentum.
Momentum Conservation and Collisionlinear momentumelastic collisioninelastic collisionsigned velocity