PASCO ME-9430 Dynamics Cart with Mass - Manual (Page 12)

012-04840E Dynamics Cart
8
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Dynamics Cart. Drape the string over the pulley. Adjust the pulley so the string is level.
4. Adjust the length of the string so that the longest arrangement of masses that you intend to
use will not hit the floor before the cart has reached the end of its run. Put a loop in this end
of the string.
NOTE: The cart’s acceleration falls to zero when the falling mass hits the floor.
5. Hang enough paper clips onto the dangling loop in the string until the cart will just continue
to move without apparent acceleration when barely nudged. This small added mass will
compensate for friction in the system and will be ignored in the following calculations. The
paper clips will remain attached to the loop throughout the experiment!
6. Move a 10 gram mass from the bed of the cart to the hanging loop, and pull the cart back to
a clearly marked starting point. Determine the distance d that the cart will move from the
starting point to the bumper block and record this distance at the top of Table 3.1.
NOTE: The total mass of the system will remain constant throughout the experiment.
7. Practice releasing the cart, being careful not to give it any push or pull as you do so. The
best way to do this is to press your finger into the table in front of the cart, thereby blocking
its movement. Quickly pull your finger away in the direction that the cart wants to move. At
the instant you pull your finger away, start your stopwatch. Stop your stopwatch at the
instant the cart arrives at the bumper. To eliminate reaction time errors, have the person who
releases the cart also do the timing!
8. Determine the average time for the cart to move through the distance (d) having been
released from rest. Record the average of the four time trials in which you have the most
confidence in Table 3.1. Repeat for all of the masses given in the data table.
9. Excluding the pulley, determine the total mass of your system, M
Total
(cart, added masses,
string) and record at the top of Table 3.1. (It will be close to 1100 grams, but you might
want to check it on a balance.)
10. Fill in the table using your data and the equations given in the Theory section.