Begin with a simple demo. Take a piece of rope long enough to stretch across the front of lecture room with a 100 Newton spring scale attached to each end.
Ask for two student volunteers. Each lulls on the spring scale, held so the class can read it.
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Have them slowly increase the pull, ask the class to compare the scale readings. |
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"Force Meter" reads 9.8 10N |
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Same reading as before! Pulley doesn't change the magnitude of tension, Only it's direction |
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Still same reading! Try putting 2kg on each side. |
Last but not least.....
Now what happens? Useful as an introduction to "loss of tension" |
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Stretch a string between the two vertical supports, right behind the spring scale to keep it from turning as it moves |
