Circular Motion Lab: Change Speed and Radius
Explore uniform circular motion by changing mass, speed, and radius. Compare inward force, acceleration, period, angular speed, and rpm.
Free, with no sign-up.
For High school students and adults reviewing the topic.
About 8 minutes.
How does it work?
- Choose a mass, a speed, and a positive radius.
- Compare the inward and tangential directions in the diagram.
- Use presets and the output table to check both challenges.
What will you get?
Distinguish velocity direction from inward acceleration and compare speed and radius effects.
What does the model assume?
- The object is treated as a particle moving at constant speed in a horizontal circle.
- The output force is the required net inward force, not a separate additional interaction. The model does not identify which physical force supplies it.
- The relations are a = v²/r, F = ma, T = 2πr/v, and angular speed = v/r. A revolution contains 2π radians and a minute contains 60 seconds.
- At zero speed the object is stationary. Acceleration, force, angular speed, and rpm are zero; a completed-revolution period is unavailable.
- The diagram is a top-down snapshot. Arrows show direction, not magnitude, and the drawing uses a fixed display size.
- Numbers are illustrative. Friction, drag, changing speed, and extended-body rotation are outside this particle model.
Which setup would you like to try?
What can you change?
Range: 0.5 to 10 kg.
Range: 0 to 20 m/s.
Range: 0.5 to 20 m.
What does the model predict?
| Quantity | Value | Unit |
|---|---|---|
| Inward acceleration | 8.0000 | m/s² |
| Net inward force | 16.0000 | N |
| Period | 3.1416 | s |
| Angular speed | 2.0000 | rad/s |
| Revolutions per minute | 19.0986 | rpm |
Solid arrow: tangential velocity. Dashed arrow: inward acceleration. Arrow lengths do not encode magnitude.
Can you reach these targets?
Begin with 2 kg moving at 4 m/s on a 2 m radius. Keep the mass, double the speed, and adjust radius to preserve the inward force.
- Target: Mass = 2 kg; tolerance 0 kg.
- Target: Speed = 8 m/s; tolerance 0 m/s.
- Target: Net inward force = 16 N; tolerance 0.001 N.
For a 2 kg object on a 5 m radius, find a speed giving 5 m/s² of inward acceleration.
- Target: Mass = 2 kg; tolerance 0 kg.
- Target: Radius = 5 m; tolerance 0 m.
- Target: Inward acceleration = 5 m/s²; tolerance 0.001 m/s².