Bouncing Ball Lab - Individual Version
Physics
Name:
Period:
Everyone has seen and played with a bouncing ball many times in their life. Because it is such a
ubiquitous experience, it is an ideal situation to apply our new understanding of energy. It is also a good
illustration of all the important concepts about energy, so studying it will prepare us to talk about the
energy involved in any other event or situation. So let’s see what a bouncing ball has to teach us about
energy.
Materials
LabPro
Motion Detector
Rubber Ball
Laptop Computer
Procedure
0. Based on the physics we already know about falling objects and our equation for different types of
energy, predict how the gravitational potential energy and kinetic energy will change as the ball
bounces. We will also predict what will happen to the total amount of energy the ball has. Draw your
predictions as a graph in the space provided on the next page. Below each prediction, explain the
reasoning behind your prediction. Clearly indicate on each graph different points (top, ground, going
down, going up) during the fall or bounce of the ball. Label the axes of your graphs clearly.
1. Turn on your laptop computer and log in. Once your computer is working, open a web browser and
steer to the Bouncing Ball Lab section of the Energy Unit portion of the Lakeridge Physics webpage
(http://lhs.loswego.k12.or.us/z-pricem/Physics/08 Energy/02 Bouncing Bal Lab/Bouncing Ball
Lab.html).
Download two files from the webpage onto your computer:
The first file is an experiment for the LabPro data acquisition interface. It is titled “Ball Bounce
Lab Individual.cmbl”. You will have to right click on the hyperlink and choose “Save Link
As…” to save a copy of it to your computer (the desktop is the simplest place).
The second file is an Excel spreadsheet for you to use in analyzing your data. You can simply
click on the link and it should give you the option to open the file with Excel, which is exactly
what you want to do. If that doesn’t work, then follow the same procedure you did for the
LoggerPro experiment file.
2. You and your partner will bring your laptop computer up to one of the stations in the front of the
room. Connect the laptop to the LabPro interface with the USB cable there and open up the LoggerPro
program.
Once LoggerPro is running and shows connection to the LabPro – there will be a little green LabPro
icon in the upper left portion of the screen – then open the experiment file that you opened earlier.
3. Measure the mass of the ball on the balance provided at the station.
One partner will hold the ball about 40 cm below the motion detector and then drop the ball and step
back when they hear the motion detector start clicking. The other partner will click the collect button
when the first partner is ready, then watch the data fill into the data table and the graphs until the
program stops collecting data.
You may have to repeat the process many times as you learn how it works. You should also repeat if
your data has any problems – like spikes in the graphs caused by the ball bouncing out from below the
motion detector – that disrupt your data.
4. Click in the data table in LoggerPro and then select all of the data with the “Select All” command
[under the “Edit” menu or ctrl+A]. Then switch to your excel spreadsheet, select cell A4 and paste all of
the copied data. Notice that there are a few columns of data that don’t show up – that data is still there,
but it is hidden to keep things simpler. This means that you will never use column B or column D.
5. Notice that column F is titled Gravitational Potential Energy, column G is titled Kinetic Energy and
column H is titled Total Kinetic and Gravitational Potential Energy. Fill in formulas for the cells in
those colums to calculate those values based on the data that you have collected.
A formula in Excel starts with an equal sign (=) in the cell that you want and then uses simple math
operations [addition (+), subtraction (-), multiplication(*), and division (/)] on the numbers from other
cells. You refer to the number in another cell by the cell’s address – if you want to use the height value
from your first data point, you would type in cell E4.
When you copy and paste a formula, it changes what cells it refers to. If you copy it one cell lower
than it was written, it looks one cell lower for all the data used in the calculation. Test this out by
copying and pasting your calculation into a lower cell and see what it does. This feature is really handy
when you want to do the same kind of calculation over and over on new data (like we do) but sometimes
you want the program to always use the same number – in that case you write the name of the cell with
dollar signs before the letter and number [for example, cell $E$4]
6. Use Excel to make a graph of the Gravitational Potential Energy of the ball over time. Select the
Gravitational Potential Energy column by clicking on the “F” above the data cells.
Once you have the two columns select “Chart” under the “Insert” menu and follow the steps in the
dialog box.
First, select a Line Graph for the Graph Type and hit the “Next” button.
Second, make sure that the values listed for the graph run the full range of your data and set the
graph so that it uses time on the x-axis. Click on the “Series” tab to get to the information we
need. Look at the line titled “Values” and make sure it reads “=Sheet1!$F$2:$F$101”. Fix it if it
is wrong. To make the x-axis right, find the line titled “Category (X) axis labels:” and click on the
little box on the far right of the space. The window will get a lot smaller, which allows you to
select the Time column by clicking on the “A” above the column. Hit the little box again and then
the “Next” button.
Third, fill in the correct values under the six different tabs to make your graph follow the
requirements for a graph in this class – you can always fix it if you don’t get it perfect here, but it
is better to get it right the first time.
Finally, select a location for the graph you have made. Choose “As new sheet:” and give the new
sheet an appropriate name. Then click the “Finish” button and behold your glorious graph.
7. Follow the same procedure as step 6 to create graphs for Kinetic Energy over time and Total Energy
over time.
8. Answer the analysis questions in the space provided. Discuss the answers in your group and then as
a class. Take notes on the discussion so that you can fix your answers.
9. Be sure to save your file and email it to yourself so that you can do any remaining work at home. If
you email it to your school account, you can access that from home by going to
http://mail.loswego.k12.or.us.
You will hand in:
Your prediction graphs from your lab packet.
Printed copies of your data graphs. The graphs should have any big events – top of a bounce, hitting
the ground, etc – clearly identified on the graph.
Answers to the analysis questions. The answers will be typed – you can get a copy of the analysis
questions to type your answers on from the Lakeridge Physics webpage.
A succinct summary of what you learned in the course of this activity.
Predictions
Ug vs. t (the amount of gravitational potential energy the ball has as it bounces)
Rationale:
K vs. t (the kinetic energy that the ball has as it bounces)
Rationale:
E vs. t (the total amount of energy the ball has as it bounces)
Rationale:
Analysis
1. Describe the ball’s kinetic energy graph. How does the amount of kinetic energy the ball has change
at different points in the ball’s bounce?
2. Where in the bounce is the ball’s kinetic energy greatest? Where is it least? Explain why those points
have the highest and lowest amount of kinetic energy. How would we see the difference in KE?
3. Describe the ball’s gravitational potential energy graph. How does the amount of gravitational
potential energy the ball has change at different points in the ball’s bounce?
4. Where in the bounce is the ball’s gravitational potential energy greatest? Least? Explain why those
points have the highest and lowest amount of gravitational potential energy. How would we see the
different in gravitational potential energy? How does this correspond with the ball’s speed?
5. Describe the graph of the ball’s total energy. How does the total amount of energy the ball has
change at different points in the ball’s bounce?
6. What do you notice about the total amount of energy that the ball has during one bounce – from the
point where it leaves the ground until it hits the ground again? Does this make sense? Why or why not?
7. What do you notice about the total amount of energy that the ball has when it hits the ground? Does
this make sense? Why or why not?
8. What do you notice about the total amount of energy that the ball has from one bounce to the next –
compare the total energy before it hits the ground to after it hits the ground? Does this make sense?
Why or why not?
Summary
In a succinct paragraph, describe the aspects of work and energy that this activity illuminated. What did
you see and learn in the course of doing this activity? (Be sure to discuss how each major point shows
up in your data.)