PURPOSE: To illustrate forces in an accelerating system.
DESCRIPTION: A rigid frame hangs from a spring scale as photographed. In the frame, a mass hangs from a spring. The mass is pulled down and attached to a hook at the bottom of the frame by a short thread loop. (Ask your students how this affects the weight shown by the spring scale.) In this position the spring scale reads about 8 Newtons. Q: When the string is burned, releasing the mass, will the reading on the spring scale immediately after the string breaks (a) increase, (b) decrease, or (c) stay the same? A: It will increase.
SUGGESTIONS: Ask your students what will happen, and why, before doing the experiment.
REFERENCES: (PIRA 1G30.20)
EQUIPMENT: Mass hanging from spring in frame hanging from spring scale, as photographed.
SETUP TIME: None.
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