Work and Energy
Objective
We
are
experimenting
with
kinetic and potential energy and relating
these
to
work.
This
is
being
accomplished using a cart rolling across
a track that is either level or elevated.
Exercise 1: Getting a Handle on Work
To measure the net work on the system, we first elevate the ramp using a wooden
block placed beneath the ramp to an angle of 4.73°. Then we attach a spring scale to tow
the ramp up the slope at a constant speed with both an angle of 0° to 60° relative to the
ramp. We take the readings from the spring scale to determine the work done by the
towing, and also calculate the work done by gravity and the work due to the normal force.
These calculations are shown below.
Calculations:
J
m
N
d
F
W
Spring
Spring
Spring
3675
.
)
0
cos(
5
.
735
.
)
cos(
=
⋅
⋅
=
=
φ
)
90
cos(
)
90
cos(
)
90
cos(
α
+
+
=
+
=
d
mg
d
F
W
Gravity
Gravity
J
m
s
m
kg
4045
.
)
73
.
4
90
cos(
5
.
)
73
.
4
90
cos(
81
.
9
002
.
1
2

=
+
⋅
⋅
+
⋅
⋅
=
J
d
F
W
Normal
Normal
0
)
90
cos(
=
=
Data:
The following is the recorded and calculated data from exercise 1:
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 Fall '06
 Cerruti
 Physics, Energy, Force, Potential Energy, Work

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