Collision Lab: free physics simulation
Balls collide in 1D or 2D. Momentum is conserved; kinetic energy depends on elasticity.
▶ Open the simulationFree, no sign-up. Works on phones, tablets and laptops.
The science
In every collision the total momentum stays the same. In an elastic collision kinetic energy is also conserved; in an inelastic one some kinetic energy turns into heat and sound. The coefficient of restitution measures how bouncy a collision is.
m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂
Things to try
- Collide equal masses elastically: they swap velocities.
- Set elasticity to zero so the balls stick together.
- Try a heavy ball hitting a light one and the reverse.
Topics covered
momentum elastic inelastic kinetic energy restitution
How to use it
Open the simulation, then change the experiment live with the sliders, checkboxes and buttons in the side panel. Drag objects on screen where it makes sense, and use Pause, Step, Speed and Reset in the bottom bar to study every moment.
Frequently asked questions
What does the Collision Lab simulation show?
In every collision the total momentum stays the same. In an elastic collision kinetic energy is also conserved; in an inelastic one some kinetic energy turns into heat and sound. The coefficient of restitution measures how bouncy a collision is.
What is the key equation?
m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂
Is the Collision Lab simulation free?
Yes. It runs free in any web browser on phones, tablets and laptops, with no sign-up or download.
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