Explore the Collisions & Momentum Lab
Crash two carts together and compare momentum and kinetic energy before and after. Free, no signup, runs in your browser.
- Free to use
- No signup
- Nothing to install
- Runs in your browser
Illustration. Open the tool for the real thing.
See it in action
The Collisions & Momentum Lab with sample data entered and the result showing.
What is the Collisions & Momentum Lab?
Crash two carts together and compare momentum and kinetic energy before and after. It runs in your browser, so a change to a setting or a drag on an object shows up at once.
Momentum conservation is used in car-crash safety design, billiards, rockets and particle physics experiments.
3 steps to your result
Open the tool and follow along. Nothing to install.
What you get
Total momentum is conserved in every collision without outside forces.
Kinetic energy is conserved only in perfectly elastic collisions.
In a perfectly inelastic collision the carts stick together and lose the most kinetic energy.
Run an elastic collision with equal masses.
Make it perfectly inelastic and read the energy lost.
Make one cart much heavier.
Used for
Pick one to see how it fits.
Physics learners
Physics students in middle school, high school and first-year university, teachers who want a quick demonstration for the projector, and anyone revising for exams.
Try it freeTeachers
For teachers: project the Collisions & Momentum Lab on the board, let students predict the result, then run it together and test this: Make it perfectly inelastic and read the energy lost. For students: change one thing at a time and write down what changes.
Try it freeHow it compares
A plain look at this tool next to the usual alternative.
| This simulation | Textbook diagram | |
|---|---|---|
| Interactive | Drag, tap and change settings | Fixed picture |
| Install | Nothing to install | Not needed |
| Cost | Free to use | Depends on the book |
Questions people ask
What is the difference between elastic and inelastic collisions?
Both conserve momentum, but elastic collisions also conserve kinetic energy. Inelastic collisions turn some kinetic energy into heat, sound or deformation.
Where does the lost kinetic energy go?
Into other forms such as heat and sound, and into changing the shape of the objects.
Is the Collisions & Momentum Lab free to use?
Yes. The Collisions & Momentum Lab is free, needs no signup or download and runs in your web browser. It is part of the Physics group of AZRS simulations.
Does the Collisions & Momentum Lab work on a phone or tablet?
Yes. The Collisions & Momentum Lab takes touch input as well as mouse input, so you can use its 5 adjustable settings with a finger. A larger screen makes the controls and graphs easier to read.
How do I use the Collisions & Momentum Lab?
1. In the Collisions & Momentum Lab, use the controls to change Red cart mass, Red cart velocity, Blue cart mass, Blue cart velocity, Elasticity. The simulation reacts instantly. 2. In the Collisions & Momentum Lab, pick an option such as Sticky (inelastic), Bouncy-ish, Elastic to switch modes or load an example. 3. In the Collisions & Momentum Lab, press "Run", "Reset" to start, reset or change what is happening. 4. Start with this experiment: Run an elastic collision with equal masses. Drag any glowing handle, object or slider with your mouse or finger and the Collisions & Momentum Lab responds in real time. 5. Change one setting at a time and watch which readout moves, then compare it with this idea: Total momentum is conserved in every collision without outside forces.
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Try the Collisions & Momentum Lab now
Crash two carts together and compare momentum and kinetic energy before and after. Free to use.
Try it free