PASCO ME-6831 Ballistic Pendulum_Projectile Launcher - Manual (Page 42)

P r o j e c t i l e L a u n c h e r E x p . 8 : P r o j e c t i l e V e l o c i t y — A p p r o x i m a t e M e t h o d
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38 012-05375C
• NOTE: It may be easier to balance the pendulum on the edge of a ruler or similar object.
5. Reattach the pendulum to the upright, making sure that it is facing the right way. Be sure that the angle indica-
tor is in front of the long pin of the pendulum.
6. Load the launcher, and then 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.
7. Fire the launcher, and record the angle reached by the pendulum in Table 8.1. 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 8.1
M = ____________________ m = ____________________ R
cm
= ___________________
Calculations
1. Find the average angle reached by the pendulum and record the value in Table 8.1.
2. Calculate the muzzle velocity of the ball fired from the projectile launcher.
Questions
1. Is there another way to measure the muzzle velocity that you could use to check your results? You may want
to use that second method and compare the two answers.
2. What sources of error are there in this experiment? How much do these errors affect your result?
3. It would simplify the calculations if kinetic energy were conserved in the collision between the ball and the
pendulum (see “Ballistic Pendulum Theory” in the Introduction). What percentage of the kinetic energy is lost
in the collision between the ball and pendulum? Would it be valid to assume that energy was conserved in that
collision?
4. How does the angle reached by the pendulum change if the ball is not caught by the ball catcher? You may test
this by turning the pendulum around so the ball strikes the back of the ball catcher. Is there more energy or
less energy transferred to the pendulum?
Table 8.1: Data
Item Value

1

2

3

4

5
Average 
Muzzle velocity