Station One:
Materials:
CBL with photogate, pulley, cart (mass
m
1
= 222 g), masses to put on cart (
m
2
), string, masses to put on string (
m
3
).
.
Directions:
1)
Put
m
2
= 700 grams on the cart.
Use hanging mass
m
3
= 50 g.
Use the EASYDATA program to monitor
the motion of the cart.
2)
Copy speed vs. position data (ignore acceleration and time).
Calculate the square of the speed.
3)
Repeat the trial with mass
m
2
= 550 g on the cart and hanging mass
m
3
= 200 g.
Copy
only
the final speed
and the final position of the cart.
At home:
4)
Tabulate the data in step #2 and graph the square of the speed vs. position.
Position is the independent
variable.
At home:
5)
Determine the square of the initial speed of the cart from the graph.
If your table was sloped, this number
may be negative.
At home:
6)
For data graphed in step #4 (including at
x
= 0 and
t
= 0), calculate the quantity
2
1
2
3
1
()
2
m
m
m v
.
This is
the kinetic energy,
K
, of the system.
Also calculate the change in kinetic energy,
K
=
K
–
K
o
, where
K
o
is
the initial kinetic energy (at
x
= 0 and
t
= 0).
Finally, calculate the quantity
m
3
gx
, which is the work,
W
,
done on the system.
This process is easy if you use a spreadsheet like Microsoft Excel.
At home:
7)
Tabulate
K
,
K
, and
W
. Graph
K
vs.
W
.
Because work depends on position, work is the independent
variable.
Station Two:
Materials:
Spring, various small masses, rod connected to table, tape/stickers, meter stick
Directions:
1)
Hang your spring from the rod and measure its length,
x
o
(the distance from the bottom of the rod to the
bottom of the spring)
2)
Hang a 100-g mass from the spring, wait until the mass comes to rest, and then measure the new length at
rest,
x
1
.
Calculate the stretch of the spring at rest,
x
1
= x
1
- x
o
.
Repeat with 200, 300, 400, 500, and
600-g masses.