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1) Copy this diagram into your book, under the above title.
2) Write down that there are no masses on the long arm and that it is balanced.
3) Draw what happens if you hang a mass on the far end of the long arm. Write a short sentence to say what happened.
4) Hang the mass from a newtonmeter.
Write down the size of the mass on your second drawing.
5) Look at the scale on the newtonmeter, how accurate is it? How many decimal places should you use to write down your measurement?
6) Attach a newtonmeter to the end of the long arm directly above where you hung the mass. Lift the arm to a horizontal position, as it was when it was balanced. It should look like the diagram to the left (ignoring the arrows).
7) Measure the force on the newtonmeter. Is it the same as what you measured in step 4?
8) Copy this diagram into your book.
Forces always come in equal and opposite pairs. Gravity pulls down, creating weight, and tension pulls up.
9) The dotted arrows represent forces. Label these arrows in your book as "weight" and "tension".
10) Hang the mass halfway along the long arm. It should look like the diagram to your left. Draw this, nice and big.
11) Is the weight the same? Label the weight arrow with the size of the force.
12) Is the force the same? Measure it and label the tension arrow.
We write T for tension, W for weight, dT for the distance from the pivot to where T pulls from, and dW for the distance from the pivot to where W pulls from.
Experiment with changing dT and dW, keep W the same, and measure T.
13) Write down a mathematical formula which is always true when the arm is horizontal, no matter what you choose for dT and dW.
For example (this is wrong): dT + dW = T x W
14) Does your formula work with the unbalanced beam? Why or why not?
Cantilever (a beam supported at one end)
There are two cantilevers at this station. One is balanced, one is not balanced.
ONLY USE THE BALANCED ONE.
T
W
dT
dW