Pasco Scientific ME-6956, Instruction Manual And Experiment Manual

Page: 11 / 46

7
012-07558A PAScar Accessory Track Set (2.2 Meter)
®
Experiment 1: Conservation of Momentum in Explosions
EQUIPMENT NEEDED:
– 2 PAScars with Mass (ME-6950)
– Dynamics Track
– Meter stick*
– Mass balance (SE-8723)*
Purpose
The purpose of this experiment is to demonstrate conservation of momentum for two
cars pushing away from each other.
Theory
When two cars push away from each other and no n et force exists, the total momentum
of both cars is conserved. Because the system is initially at rest, the final momentum of
the two cars must be equal in magnitude and opposite in direction, so that the resulting
total momentum of the system is still zero.
Therefore, the ratio of the final speeds of the cars is equal to the ratio of the masses of
the cars.
To simplify this experiment, choose the starting point for the cars at rest, so that the two
cars reach the end of the track simultaneously. To determine the speed, the distance
divided by the time, measure the distance traveled, since the time traveled by each car
is the same.
The ratio of the distances is equal to the ratio of the masses:
Procedure
1. Level the track by setting a car on the track to see which way it rolls. Adjust the level-
ing feet to raise or lower the ends until a car placed at rest on the track will not move.
2. For each of the following cases, place the two cars against each other with the plunger
of the PAScar pushed completely in and latched in its maximum position (see Figure
1.1).
Leveling foot
!
!
!
"
#
"
"
"
"
#
!
#
"
# "
"
"
"
∆
∆
p = m
1
v
1
-m
2
v
2
= 0
Figure 1.1
v
1
v
2
=
∆
x
1
∆
t
∆
x
2
∆
t
=
∆
x
1
∆
x
2
*Not included in Track Set