Energy, work and power
Drop tower
Watch gravitational energy become kinetic energy as a mass falls.
mgh = (1/2)mv²
Apparatus
- Mass
- Height scale
- Speed gate at the bottom
Method
- Set the mass and the drop height.
- Predict the speed at the bottom from (1/2)mv² = mgh. The mass should cancel.
- Release the mass and compare the gate speed with your prediction.
- Change the mass. The speed should stay the same if the height stays the same.
This bench ignores air resistance. A real drop needs a sand tray, not a foot.
Gravitational
Kinetic
Height now
5m
Speed
—m/s
GPE
20J
KE
0J
The two energy bars swap over, and their total stays constant.
Back to the Energy, work and power lesson