Name _____________________
Class ______________
Date _________
United Christian College
Data Logging Experiment 4.6
Work–Energy Theorem: W = ∆E (Activity P19)
I. Purpose of the Experiment:
The purpose of this experiment is to compare the work done on an object and the change in
kinetic energy of the object.
II. Background:
For an object with mass m that experiences a net force Fnet over a distance d that is parallel to the
net force, the work done is:
W  Fnet d
If the work changes the object’s vertical position, the object’s gravitational potential energy
changes. However, if the work changes only the object’s speed, the object’s kinetic energy changes
as follows:
W  KE  KE f  KEi  12 mv f 2  12 mvi 2
where W is the work, vf is the final speed of the object and vi is the initial speed of the object.
III. Procedures:
1. Setup the experiment as follows:
Force sensor
Photogate
Cart
100 g mass
Name _____________________
Class ______________
Date _________
2. Click “Data Studio  Library  Open Activity  Physics Labs  P19 Work and energy.ds”.
3. Calibration of Force Sensor:
a. Click “Setup  Force Sensor  Calibration”
b. Type “0.00” in the “Value” of the part of “Low point”. Then push the “Tare” button on a
side of the force sensor. Finally, click the button “Take Reading”.
c. Type “0.98” in the “Value” of the part of “High point”. Use the force sensor to hang a
mass of 100 g and click the button “Take Reading” at the same time.
d. Click “ 確定 (Enter)” button to finish the calibration.
4. Click “Force v.s. Position Graph”.
5. Pull the cart away from the Photogate so the object on the end of the string is just below the
pulley. Add 100 grams of mass to the mass hanger.
6. Click “Start” button.
7. Release the cart and recording data. Before colliding on the photogate, the cart should be stopped
by your hand.
8. Click “Stop
” button.
9. Make alignment on graphs:
a. Click
(Scale to fit)
b. Press the left button of the mouse and select the points that you want to obtain the area
under the graph.
10.
Click the Statistics menu button (
) and select “Area” and record the value of area as
“Work ( from integration)” in Data Table.
11.
Click the ‘Calculate’ button (
) in the main toolbar. The Calculator window
will open.
a. Change the value of mass “0.824” to “0.93”.
b. Click “Accept” button to save your change.
c. Close this “Calculator” display.
Name _____________________
12.
Class ______________
Date _________
Click “Table/Velocity and Kinetic Energy Table” button and find the maximum value of
K.E.. Record the value as “Maximum Kinetic Energy” in the Data Table.
Data Table
Item
Mass (hanging)
Mass (cart and sensor)
Value
0.1 kg
0.93 kg
Maximum Kinetic Energy
Work (from integration)
Questions
1.
What is the percent difference between the maximum kinetic energy and the work (from
integration)?
2.
What are possible reasons for the difference?