PASCO ME-9430, Инструкция по эксплуатации

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Plunger Cart Experiments
10
012-14781A
Procedure
1. Set up the pulley, cart, and a bumper of some sort to prevent the cart from hitting the pulley at the
end of its run. Add the following masses to the accessory tray of the Plunger Cart: 10-g, 50-g, 500-g,
and two 20-g masses.
2. Carefully level the table until the cart has no particular tendency to drift or accelerate in either
direction along its run.
3. Tie one end of the string to the tie point on the top of one end of the Plunger Cart. Drape the string
over the pulley. Adjust the pulley up-or-down 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 Plunger 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 Plunger Cart to the hanging loop and pull the cart back
to a clearly marked starting point. Determine the distance d that the Plunger 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 Plunger 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 Plunger Cart
arrives at the bumper. To eliminate reaction time errors, it is best that the person who releases the
cart also does 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
(Plunger Cart, added masses,
string) and record at the top of Table 3.1. (It will be close to 1100 grams, but you should check it
on a balance.)
10. Fill in the table using your data and the equations given in the Theory section.
Data Analysis
d = _________________ cm M
total
= _________________ gram
net
total
F
a
M

or
(Theoretical. Value)
total
m
a g
M
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