®
M o d e l N o . M E - 6 8 4 3
T r a d i t i o n a l E x p e r i m e n t
7
Untie the string from the launcher shaft and remove the pulley for the next part.
Spring Potential Energy and Kinetic Energy
1.
Place a second end stop on the track about 8 cm behind the first end stop.
2.
Elevate one end of the track by about 20 cm.
3.
Hold the cart on the track with the launcher shaft through the hole in
the first end stop, and with the spring just touching the end stop, but
not compressed. Record this position of the cart as
x
1
.
4.
Push the shaft through both and stops and put the release pin into the shaft. Let
the pin rest against the second end stop. Record this position of the cart as
x
2
.
5.
Pull out the release pin with a quick jerk.
6.
Watch the cart carefully as it ascends the track. Observe the highest position
achieved. Try to read it to the nearest centimeter. Record this position as
x
3
.
7.
Calculate the spring compression:
x
=
x
1
-
x
2
8.
Use
x
, the value of
k
that you found in the previous part, and Equation 3 to calcu-
late the initial potential energy of the spring.
9.
Calculate the distance traveled by cart:
∆
s
=
x
3
-
x
2
10.
Measure the mass,
m
, of the cart with the cart launcher and spring attached.
11.
Measure the angle,
θ
, of the track.
12.
Use Equation 5 to calculate the change in gravitational potential energy of the
cart.
13.
Compare the initial potential energy of the spring to the maximum gravitational
potential energy of the cart. Are they equal? If not, what might account for the
difference?
q
