Table 9.1, Calculations – PASCO ME-6831 Ballistic Pendulum_Projectile Launcher User Manual
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5.
Tie a loop in a piece of string, and hang the pendulum horizontally from the loop. (See Figure 9.1.) With the
ball latched in position in the ball catcher, adjust the position of the pendulum in the loop until the pendulum
balances. Measure the distance from the pivot point to this balance point, and record the distance as R
cm
.
•
NOTE: It may be easier to balance the pendulum on the edge of a ruler or similar object.
6.
Measure the distance between the pivot point and the center of the ball. Record this as R
b
.
7.
Remove the launcher so that the pendulum can swing freely. With the ball in the ball catcher, give the pendu-
lum an initial displacement of 5° or less. Using the stopwatch, time how long it takes to go through ten oscil-
lations. Divide this time by the number of oscillations and record the result as T in Table 9.1.
8.
Calculate the value of I, and record it in Table 9.1.
9.
Reattach the launcher and load it. Set the angle indicator to an angle one or two degrees less than the angle
reached in step 2. This will nearly eliminate the friction against the pendulum caused by the angle indicator,
since the pendulum will only move the angle indicator for a short distance.
10. Fire the launcher, and record the angle reached by the pendulum in Table 9.1. Repeat several times, setting the
angle indicator to an angle one or two degrees less than the previous angle reached by the pendulum each
time.
Table 9.1
M = ____________________ m = ____________________ R
cm
= ___________________
R
b
= ____________________ T = ____________________ I = _____________________
Calculations
1.
Find the average angle reached by the pendulum and record the value in Table 9.1.
2.
Calculate the muzzle velocity of the ball fired from the projectile launcher.
Table 9.1: Data
Item
Value
1
2
3
4
5
Average
Muzzle velocity
String loop
R
cm
Figure 9.1: Setup