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.
• The tube is 100 cm long.

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.

Last updated on July 25, 2024