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Inertia Ball
# 1F20.10

Description: Depending on the speed that you move the lower rod downward, the inertia of the ball will break either the top or the bottom string.

Have your students guess what sort of pull will snap which string.

Instructions: This demo will be set up when you arrive. There will be two string segments tied to the bottom of the ball, and one to the top.

First, insert bar the through one of the loops below steel ball and pull down quickly. This will snap the string below the ball.

Second, insert the rod through the remaining loop below the ball, and pull down very slowly. This will snap the string above the ball.

Hazards: The steel ball weighs about 1300 grams! You will have to make sure you hold the rods at the farthest ends to make sure that your hands are out of the way of the falling ball. Care should also be taken make sure the ball doesn't roll off the table and injure your foot.

Parts: Large steel ball
Short pole

Purchased/Built: purchased

Setup Time: 10 min

Quant. in Demo Room: 1

Source: Central Scientific

Demo References
The Video Encyclopedia of Physics Demonstrations Disc 02-13 A mass is suspended between two cords. Pull slowly or jerk on the lower cord.
Sutton M-100 Break the string on the top or bottom of a suspended mass.
Freier and Anderson Mc-2 Two steel balls are suspended by strings with identical strings tied from their bottoms. Give a quick jerk to one and pull the other slowly.

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