Education Prize Logo
Science SPORE Prize
November 2011

NSF Logo
The Open Source Physics Project is supported by NSF DUE-0442581.

Falling Cup with Ball Model Applet Page

Falling Cup with Spring and Ball

The weightless freefall of two masses connect by a spring appears in many physics demonstration catalogs and websites. Search the Physics Instructional Resource Association website for PIRA 1G20.40. A description of the apparatus and a video of this demonstration is available on the University of Maryland Physics Demonstration website.

The Falling Cup with Ball model shows a mass attached to the inside of a cup with a light spring. The cup is held upside down, with the mass hanging out of the cup, then released from rest. What happens when the cup is released?

  1. The mass will extend the spring, like a parachute, due to air pressure pulling on the cup.
  2. The mass will be pulled up into the cup by the spring?
  3. The cup will fall with the mass in its original position?
Additional information on this applet can be found in the Open Source Physics comPADRE collection.
The OSP Network:
Open Source Physics - Tracker - EJS Modeling
Physlet Physics
Physlet Quantum Physics