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1C20.10 - The Feather and the Farthing

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​1C20.10 - The Feather and the Farthing

Title1C20.10 - The Feather and the Farthing

Demonstrate that all objects fall with the same speed in a vacuum.

Assembly Instructions

The pump cart is pre-assembled. Connect the feather and farthing chamber to the external chamber tube. Close the valve to the main pump chamber and open the valve to the external chamber. Before running the demo, make sure that the vent valve is closed.
Plug in the solenoid to the cart and test to make sure that it releases the feather and farthing.

Setup Time10
Operation Time
Preview Time5
Operation Instructions


1   Close Vent
2   Open External Valve
3   Turn on the solenoid and attach the feather and farthing
4   Turn on Vacuum Pump (pump to ~28)
5   Launch Feather & Farthing w/ solenoid
6   Open the vent valve and equalize the chamber.

Demo on DimeNo
PIRA 200Yes
Export Instructions (if different)

One of Galileo's most famous observations was that objects of different mass will fall at the same rate due to gravity or acceleration from the earth is the same for objects irrespective of mass.

This was the basis of Galileo's storied experiment on the Tower of Pisa and repeated on the moon during the Apollo 15 mission with a feather and a hammer.

Category1 Mechanics
Subcategory1C - Motion in One Dimension
Keywordsacceleration due to gravity, uniform acceleration
Construction Information
vacuum pump - mounted on cart, with bell jar
plexiglass tube - 53", with vacuum hose attachment
top plate with holding solenoid
paper feathers with wiffle ball
power supply - 28VDC