PIRA 1C20.10 Uniform Acceleration:
Penny and Feather
Picture shows the demonstration as used at the University of Texas
at Austin.
Instructions / Notes:
- Demonstration includes a plastic tube containing a penny and a feather.
- 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 the pump running for 30 seconds.
- Close the valve by moving it to a PERPENDICULAR CLOSED position BEFORE turning off the pump.
- Disconnect the hose from the tube.
- Flip the tube QUICKLY to demonstrate that the penny and feather now fall at the SAME rate.
- Return the valve to the PARALLEL OPEN position to allow air back into the tube.
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.
- The tube is 100 cm long.
Demo Staff:
- CLAMP THE TUBE STAND TO THE 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.
- Parts included: Tube, hose, two valve clamps, penny, two feathers.
