Torque & Rotational Inertia Lab
Push a wheel at different distances from its axle and see torque, moment of inertia, angular acceleration and angular momentum.
Push the wheel with a force at a distance from the center. A bigger force or a longer lever arm gives more torque. A heavier wheel resists spinning more. Drag the red handle to move where you push.
About the Torque & Rotational Inertia Lab
Free torque & rotational inertia lab. Push a wheel at different distances from its axle and see torque, moment of inertia, angular acceleration and angular momentum. Drag, change the sliders and see the result live. No sign-up, works on phone and computer. Built for physics, the torque & rotational inertia lab runs instantly in your browser: change a setting or drag an object and the result updates at once, so you learn by trying things out rather than only reading about them.
Push a wheel at different distances from its axle and see torque, moment of inertia, angular acceleration and angular momentum. Use it to explore physics ideas at your own pace, then check what you found against the key ideas further down this page.
How to use the Torque & Rotational Inertia Lab
- Use the controls to change Push force, Lever arm (distance from axle), Wheel mass, Friction torque, Shape. The simulation reacts instantly.
- Pick an option such as Solid disk, Ring (hoop) to switch modes or load an example.
- Press "Push: on", "Stop wheel" to start, reset or change what is happening.
- Where you see a glowing handle, object, weight or atom, drag it with your mouse or finger. Everything responds in real time.
- Watch the readouts and graphs update as you experiment, and compare what you see with the key ideas below.
Things to try
- Double the lever arm and watch the torque double.
- Switch from a disk to a ring and compare the angular acceleration.
- Turn on friction and find the smallest force that starts the wheel turning.
- Stop pushing and see how friction slows the wheel.
Key ideas you can learn
- Torque = force × lever arm, so pushing farther from the axle is more effective.
- Angular acceleration = torque ÷ moment of inertia.
- A ring is harder to spin than a solid disk of the same mass because its mass is farther from the center.
- Angular momentum = moment of inertia × angular speed.
Where this is used in the real world
Wrenches, gears, engines, flywheels, helicopters and figure skaters spinning faster by pulling in their arms all use torque and rotational inertia.
Who is this simulation for?
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. It works well for flipped classrooms because students can explore before the lesson.
For teachers: project it on the board, let students predict what will happen, then run it together. For students: change one thing at a time and write down what changes.
Frequently asked questions
What is moment of inertia?
It measures how hard it is to change how fast something spins. It depends on the mass and on how far that mass is from the axis.
Why is a door handle far from the hinge?
A longer lever arm gives more torque for the same force, so the door opens more easily.
Is the Torque & Rotational Inertia Lab free to use?
Yes. It is completely free, with no signup, no download and no ads inside the simulation. It runs in your web browser.
Does the Torque & Rotational Inertia Lab work on a phone or tablet?
Yes. It uses touch as well as the mouse, so you can drag objects with your finger. A larger screen makes the controls easier to see.