PURPOSE: To illustrate inertia of motion.

DESCRIPTION: If a plastic straw (like those from McDonald's) is pushed slowly into a raw potato, the rigid potato will cause the softer plastic straw to bend and break. However, if a significant velocity is given to the straw it can be pushed clean through the potato. This is what often happens in a tornado, where apparently softer objects are accelerated to high speeds by the wind and driven through apparently harder objects.

SUGGESTIONS: Making a loud karate scream just before thrusting the straw helps a lot. What might happen if the straw hits your hand?

REFERENCES:

EQUIPMENT: Potato (furnished by instructor) and plastic straw, as photographed.

SETUP TIME: None (if potato available).

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