Name: ___________________________
Block: __________
Date: __________________
Work – Energy Theorem Lab
Purpose: The purpose of this lab experience is for students to have a better understanding of the relationship between
work and energy.
Pre-Lab Questions:
1. A block of wood is sitting at rest on a table. A passing student pushes the block and it begins to slide.
a. Was work done on the block?
________________________________________________________________________
b. What happened to the kinetic energy of the block when it was pushed?
________________________________________________________________________
c. Eventually the block will slide to a stop, why? Where does the kinetic energy go?
________________________________________________________________________
2. Does putting effort (a force) into something always mean work is being done? Why or Why not?
______________________________________________________________________________
3. Suppose you are president of the Load -n‘ Go Company. A local college has three jobs (see below) it needs to
have done and it will allow your company to choose one before offering the other two jobs to rival companies.
All three jobs pay the same total amount of money.
Which one would you choose for your crew? Explain why.
___________________________________________________________________________________________
___________________________________________________________________________________________
___________________________________________________________________________________________
Name: ___________________________
Block: __________
Date: __________________
Materials:
1 – Dynamics Cart
1 – Wireless Dynamics System (WDSS)
1 – Dynamics Track
Digital Balance
1 – Motion Detector
1 – Block of Wood
Procedure:
Procedure to Set up the Sensors & Equipment.
1.
2.
3.
4.
Plug the USB cord from the Motion Detector into the WDSS (port is on the side).
Turn on the LabQuest 2.
Turn on the WDSS.
Connect the WDSS to the LabQuest 2
a. Sensor  WDSS Setup  Scan  Select the Name of your Lab Groups Device.  Select Force 
Select OK.
Experiment 1: Providing Evidence to Support the Work Energy Theorem
1. Measure the mass of your dynamics cart and WDSS using the digital balance. Record the value in the data
table. Make sure you convert Grams to KILOGRAMS
2. Setup the sensors and track as indicated in the diagram below. Make sure your track is level.
3. Place the cart 20 cm in front of the detector and have the force sensor hook pointing away from the
detector.
4. Turn on and setup the WDSS (See Instructions on Board)
5. Press Play on the LabQuest 2 to begin collecting data.
6. Slowly pull the cart away from the motion detector. You should use a constant force and the cart should
gently increase in speed. Stop when you get to the end of the track. (See the example graphs below, your
data should match the SHAPE)
Figure 1: General Shape of Graph
7. Switch the top graph to show the Velocity – Time Graph.
a. Tap the Y-Axis Label and change it to velocity.
Name: ___________________________
Block: __________
Date: __________________
8. Use the Lab Quest to how fast the cart was moving after you pushed it.
a. Highlight the region of the graph that where the velocity was increasing. (See Graph Example)
b. Go to Analyze  Statistics  Velocity
c. Record the Max Value (just the first part, not the time at which it happened) in the observation table.
Figure 2: Where to Highlight
9. Use the LabQuest to find the average force you pushed the cart.
a. Do not change what you have highlighted (don’t touch the graphs on the screen)/
b. Go to Analyze  Statistics  Force
c. Record the Mean Value in the observation table.
10. Use the Lab Quest to how far the car moved while you pulled it.
a. Change the top graph back to a Position Time Graph.
b. Go to Analyze  Statistics  Position
c. Subtract the Min position from the Max position. Record this calculated value in the data table.
11. Repeat the experiment TWO more times, pushing with different amounts of force
Observation Table
Experiment 1
Mass of Cart & WDSS (kg)
Average Force
(N)
Trial 1
Trial 2
Trial 2
Final Speed (m/s)
Distance
Travelled (m)
Name: ___________________________
Block: __________
Date: __________________
Experiment 2: Using the work Energy theorem to investigate friction
1. Measure the mass of the block of wood using a digital balance. Record this value in the observation
table. Make sure to convert grams to KILOGRAMS.
2. Setup the motion detector and the block of wood as shown in the diagram.
3. Place the block 1.0 meters in front of the detector.
4. Press Play on the Motion detector.
5. Push the block of wood so it begins to slide towards the detector. The books should start to move
and the slide to a stop BEFORE hitting the detector. (You should get graphs similar in shape to those
shown below.)
6. Use the Labquest 2 to determine the maximum speed the block reached as you pushed it.
a. Highlight the region of the graph where the speed was changing (the bump) on the VELOCITY
GRAPH.
b. Go to Analyze  Statistics  Velocity
c. Record the Max Value (just the first part, not the time at which it happened) in the observation
table.
7. Use the lab quest to determine the distance the block slid after you stopped pushing it.
a. Keep the same region highlighted that you used for Step 6 above.
b. Go to Analyze  Statistics  Velocity
c. Find the difference (subtract) between the Maximum position and Minimum Position. This is
the distance the block travelled while it was slowing down. Record this value in the Observation
table.
Observation Table
Experiment 2
Mass of Block (kg)
Maximum Speed
Distance Travelled while
slowing down.
Name: ___________________________
Block: __________
Date: __________________
Analysis
Experiment 1: Providing Evidence to Support the Work Energy Theorem
1. Calculate the distance you pushed the cart for each trial in experiment 1. Record the value in you
Analysis Table.
2. Calculate the work you did to move the cart for each trial in experiment 1. Record the value in your
Analysis Table.
3. Calculate the Kinetic Energy the cart had after being pushed for each trial in experiment 1. Record the
value in the Analysis Table.
Experiment 2: Using the work Energy theorem to investigate friction
1. Calculate the amount of kinetic energy the block of wood contained after you pushed it. Record the
value in the Analysis Table.
2. If the block of wood slows down to a stop after being pushed, determine the amount of work friction did
on the block of wood? Record this value in the Analysis Table.
3. Calculate the frictional force acting on the block of wood. Record the value in the Data Table.
Analysis Table:
Experiment 1
Distance Travelled (m)
Work Done on Cart (J)
Trial 1
Trial 2
Trial 2
Experiment 2
Initial KE (J)
Work done by Friction (J)
Force of Friction (N)
Kinetic Energy Gained (J)
Name: ___________________________
Block: __________
Date: __________________
Conclusion:
Experiment 1: Providing Evidence to Support the Work Energy Theorem
1. Does your information from Experiment 1 support the Work – Energy Theorem? __________________
a. How can you use your data to explain and justify your answer to part 1?
______________________________________________________________________________
______________________________________________________________________________
2. How did the Kinetic Energy of the cart changed as you put greater amounts of work on the cart?
_____________________________________________________________________________________
3. Draw a Free Body Diagram of the ALL the forces that were acting on the cart as you pushed it.
4. In reality, all the work you put on the cart did not turn into kinetic energy. Where did some of the work
go and what type of energy did it turn into?
_____________________________________________________________________________________
_____________________________________________________________________________________
Experiment 2: Using the work Energy theorem to investigate friction
1. How much work did you have to do on the block to get it to reach the speed you recorded in the lab?
____________________________________________________________________________________
2. Draw a Free Body Diagram of the forces acting on the block of wood JUST AFTER you stopped touching
it.
3. How much does the block of wood WEIGH? ________________________________________________
4. What is the normal force the block of wood experiences from the track? _________________________
5. Calculate the coefficient of kinetic friction between the block of wood and the track. Show your work.
 = ______________
Bonus: Use the same information you collected and calculated in the lab for experiment 2 to predict the following
scenario. This time you push the block so that it travels three times faster, how far does it slide before coming to a
stop? Do your work on a separate sheet of lined paper and staple to your lab.