Kepler's Second Law using a centripetal force kit

Class practical

The simple kit demonstrates the increase in speed with a diminishing radius of orbit.

Apparatus and Materials

For each student or group of students

• Centripetal force kit

Health & Safety and Technical Notes

Ensure that the bungs are securely attached and that each student has sufficient space to whirl the bung safely.

The centripetal forces kit is available from:

Technology Supplies Limited

Procedure

1. Set the bung whirling around the top of the apparatus.
2. Pull on the thread to increase the load.

Teaching Notes

• Kepler's Second Law states that a planet in its orbit sweeps out equal areas in equal times. The time of orbit of the puck will fall as its radius of orbit decreases.
• You can measure the load by attaching a newton meter to the bottom of the string. As the force on the puck is increased, its orbit gets smaller and its speed increases.