Plunger Cart
Experiments
18
012-14781A
Procedure
1. Set up the system as shown in Figure 5.1. Position the cart so that its plunger hangs over the edge
of the table several centimeters.
NOTE: You will need a long, horizontal table, or board for this experiment. A 3/4 inch by 1 foot by
8 foot plywood board is recommended.
2. Arrange to have a stop of some sort to insure that you always use the same pullback angle for the
hanging meter stick.
3. Pull the meter stick or rod back to the pullback angle that you have chosen and release it, allowing
it to strike the cart plunger. Record the corresponding values of y and x in Table 5.1.
4. Repeat step 3 four times for each value of y, changing it from roughly 10 to 90 cm in 10 cm increments.
5. Compute the average value of x for each value of y.
6. By interpolation, determine the location of SS1 from your data and record it below Table 5.1.
7. Using Eqn. 1, compute the location of SS2 and record it below Table 5.1.
8. If time permits, repeat the above after either repositioning the pivot (i.e. “choking up”) or adding 100
grams or so at some point on the stick.
NOTE: This would add a little realism to the experiment since neither a bat nor a tennis racket is
uniform!
Table 5.1
y-position of SS1 = _________ cm y-position of SS2 = _________ cm
Questions
1. Is it possible to construct a “Superbat” for which both SS1 and SS2 coincide? If so, what changes
would have to occur to the uniform rod to bring SS1 and SS2 closer together? (You might use the
SweetSpot computer program to help you answer this!)
2. What assumptions have we made in analyzing this system? How do they affect our results?
Trial
y (cm)
x (cm)
Average x
(cm)
Optional µmgx
(joules)
1
10
________ ________ ________ ________
2
20
________ ________ ________ ________
3
30
________ ________ ________ ________
4
40
________ ________ ________ ________
5
50
________ ________ ________ ________
6
60
________ ________ ________ ________
7
70
________ ________ ________ ________
8
80
________ ________ ________ ________
2
1 mv
mgx
2
Eqn. 2