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Discuss with the children the concept of acceleration. Do the
experiment as a class.
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To make the measuring instrument, find a piece of a scrap wood.
Measure its width with a ruler and then cut a piece of hardboard to the
same width. The piece of hardboard should be about three times longer
than the thickness of the wood.
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Using a hammer and nail, carefully punch a hole into the hardboard in
the center. Then attach the hardboard to the wood using wood glue.
Attach a narrow piece of paper to the wood with scotch tape. Allow the
wood glue to dry and bond completely.
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Cut a piece of elastic thread. Tie one end of the thread securely to
the rear axle of a small toy truck. Stretch the other end through the
hole in the hardboard and knot it securely at the back. Then put a stone
into the bed of the truck and wrap a piece of tape around it to secure to
the truck bed.
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To calibrate the scale, hold the instrument upright so that the
weighted truck hangs, stretching the thread. Mark the scale opposite the
front of the truck with a pencil and write 1.0 against it. Next place
the instrument on a level surface and mark how far the truck can reach
without stretching the thread. Write 0 against this mark. Now divide
the distance between the two marks into ten equal parts and write 0.5
against the middle mark.
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For the next part of the experiment you will need to take the
instrument into a car and hold it horizontally. As the car is
accelerating hold the instrument with the hardboard end of the instrument
facing the front of the car you are riding in. The measurement of
positive acceleration, or speeding up will be reflected on the piece of
paper. To measure the deceleration, or the rate at which a vehicle slows
down, while in the car you are riding in, hold the instrument
horizontally with the hardboard end of the instrument facing the rear of
the car you are riding in. Mark down the results in a notebook.
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Then try using the instrument in another car and compare the results.
Take your findings back to the students for the last part of this
experiment.
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