About this experiment
An object can accelerate even when its speed stays constant, because velocity includes direction. Place a mass on a circular path and inspect the inward force arrow and tangential velocity arrow. Compare the required centripetal force as angular speed, mass and radius change.
Learning goals
- Investigate how angular speed affects tangential speed while controlling the other variables.
- Use the graph and numerical readings to test a prediction.
- Explain the physical assumptions and where this model stops applying.
How to use it
- 1Set mass to 1 kg, radius to 2 m and angular speed to 2 rad/s. Verify 8 N.
- 2Save the curve and double radius while holding angular speed fixed. Compare force.
- 3Double angular speed. Why does force increase by a factor of four?
- 4Scrub time to move around the circle. Check that the force stays inward and velocity stays tangent.
The model
Assumptions
- The path is circular with constant radius and angular speed. The force readout is the required inward net force.
- The diagram scales radius proportionally and shows directions with schematic arrows. It does not model the mechanism providing the force.
Try this in class
- Q1Why does increasing radius increase force here, whereas F = mv²/r suggests a decrease?
- Q2What happens to the motion if the inward force is removed?
Frequently asked questions
Is centripetal force an extra kind of force?
No. It names the inward net force. Tension, gravity, friction or another interaction can provide it.
What happens when angular speed is zero?
The mass is stationary. Speed, acceleration, force and frequency are zero; the period would be infinite.