PASCO ME-6814 Mini Catcher Accessory - Manual (Page 7)

012-06293A Mini Catcher Accessory
3
Experiment 1: Ballistic Pendulum
EQUIPMENT NEEDED
– Mini Launcher and steel balls (ME-6825) – table clamp
– Mini Catcher Accessory (ME-6814) – meter stick
– Universal Table Clamp (ME-9376B) – white paper, carbon paper
– Support Rod (90 cm) (ME-8738) – plumb bob
– Right Angle Clamp (SE-9444) – mass balance
optional: Photogates and Photogate Bracket
Purpose
Students will determine the percent loss of kinetic energy as a result of an elastic collision by
determining the initial and final velocities of the projectile from the Mini Launcher and by using
the laws of Conservation of Energy and Conservation of Momentum.
Theory
A ball is launched horizontally and embeds in
the bob of a pendulum. The pendulum then
swings up to a particular height, h. (See Figure
1.1.)
Figure 1.2. Conservation of Momentum
Before Collision
9 8 7 6 5 4 3 2 1 0 1 2 3 4
MINI LAUNCHER ME-6825
CAUTION
WEAR SAFETY GLASSES WHEN IN USE.
DON’T PUSH PISTON WITH FINGER! ME-6814
MINI CATCHER ACCESSORY
v
o
m
B
m
C
Launcher
9 8 7 6 5 4 3 2 1 0 1 2 3 4
MINI LAUNCHER ME-6825
CAUTION
WEAR SAFETY GLASSES WHEN IN USE.
DON’T PUSH PISTON WITH FINGER! ME-6814
MINI CATCHER
ACCESSORY
v
m
B
+ m
C
Launcher
After Collision
Momentum is conserved during the collision, but
kinetic energy is not. The momentum after the
collision is equal to the momentum before the
collision:
(1)
m
b
v
o
= m
b
+ m
c
v
where m
b
is the mass of the ball, v
o
is the muzzle velocity of the ball, m
c
is the mass of the
catcher, and v is the velocity of the catcher (and ball) after the collision. (See Figure 1.2.)
ME-6814
MINI CATCHER
ACCESSORY
ME-6814
MINI CATCHER
ACCESSORY
Figure 1.1. Conservation of Energy
h
v
v = 0