PIRA 1C20.10 Uniform Acceleration: Penny and Feather
Photo shows the demonstration used at the University of Texas
at Austin.
Concepts Conveyed:
- In a vacuum, objects falling from the same height will reach the ground at the same time regardless of mass and shape.
- Under normal conditions, air resistance affects the rate at which the objects fall.
Instructions / Notes:
- Before creating the vacuum, flip the tube quickly to demonstrate that the penny and feather fall at different rates.
- Connect the red hose to the vacuum valve by tightening the clamp around the nozzle.
- With the vacuum valve in the parallel open position, turn on the vacuum pump using the red switch. Leave pump running for 30 seconds.
- Close the valve by moving it to a perpendicular closed position before turning off the pump and disconnecting the hose.
- Flip the tube quickly to demonstrate that the penny and feather now fall at the same rate.
- Return the valve to the open position to allow air back into the tube.
Demo Staff:
- Clamp tube stand to table.
- OPEN VALVE: valve knob is PARALLEL to the vacuum hose and to the tube.
- CLOSED VALVE: valve knob is PERPENDICULAR to the vacuum hose and to the tube.
