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Paint Cans
Here is a paint can with a stiff lid.
The experiment is simple, but you need at least three people to do it.
Record your results as a scatter plot as you go. This means you draw a mark for every measurement you take but do NOT join them up with a line.
When you have taken all your measurements, draw a line of best fit on the graph. Is it straight or curved?
Everybody should draw their own scatter plot. Stick it in your book.
Push the lid down hard.
One person inserts the lever under the lid edge and gently holds the other end of the lever, just so that it doesn't slip. This person is not trying to open the can.
One person chooses any point along the lever and measures
the distance FROM THE CAN to the chosen point
(this is NOT the distance from the handle to the point)
Then this person attaches a newtonmeter to the chosen point and gently holds it in place with a finger. Again, just to stop it slipping.
One person slowly pulls on the newtonmeter until the can opens and reads the size of the force.
IMPORTANT! Do not use a lot of force! If you reach the limit of the newtonmeter, STOP THE EXPERIMENT and ask for help.
The force will go up first and then down when the lid comes off. Record the maximum force you saw. Repeat at different positions along the lever.
Measure this distance
Measure this force
This is a right angle
Don't slip!