Subject Area:
Physics
Associated Lesson:
Projectile Motion
Activity Title:
The Catapult
Header:
Grade Level:
10 -12
Activity Dependency:
Minimal with building. More help involved with engineering questions and solving math
problems.
 Note to teacher: Student teams (pairs work best) should be encouraged to come up with
their own design, independently from other groups, the Internet, etc. Therefore, it is
better if this is assigned in class before students can research designs.
Time Required:
30 min to construct
15 min calculations
15-30 min engineering applications
Group Size:
2 students per group. If there are more students to a group for this activity, there is probably not
enough for each student to work on.
Expendable Cost per Group:
$10.00
Summary:
In a two-person team, construct a mechanism that will catapult the provided projectile to the
prescribed target with the material provided.
Engineering Connection:
Engineering design often involves the creative use of components for something other than their
original intent.
Engineering Category:
Relates science concept to engineering; chiefly mechanical engineering with some aspects of
civil and structural engineering.
Keywords:
Catapult, initial horizontal velocity, initial vertical velocity, resultant speed, resultant direction,
horizontal acceleration, vertical acceleration, trebuchet, efficiency, projectiles, physics, activity
Alabama Course of Study Standards:
ALCOS: 1.) Explain linear, uniform circular and projectile motion using one and two
dimensional vectors. 4.) Describe quantitative relationships for velocity, acceleration, force,
work, power, potential energy, and kinetic energy.
Pre-Requisite Knowledge:
Catapult use and Physics applications. Basic understanding of vectors, velocity in two
dimensions, forces, and acceleration. Concepts concerning energy and even momentum are also
helpful for a deeper understanding.
Learning Objectives: Students should be able to-1. Discuss uses of catapults in industry and the connections to engineering.
2. Discuss uses of catapults and similar instruments throughout history.
3. Exhibit decision making skills.
4. Demonstrate higher-level thinking about uses of different materials to construct a
mechanism.
5. Cooperate with a partner to solve problems, design, build, and test the mechanism.
6. Measure time and range of projectile.
7. Calculate horizontal, vertical, and resultant velocities (including the angle) of the
projectile.
8. Calculate the forces on the projectile.
9. *Optional, depending on instructor: Calculate quantities related to energy and/or
momentum.
10. Demonstrate ability to work within time and materials constraints.
11. Show overall improved knowledge and skills regarding physics concepts and their
applications to engineering.
Materials List:
You will receive a paper bag containing the following materials. All of these materials
(including the bag) can be used in the construction of the device. You are also allowed to use up
to two 8 ½’’ x 11’’ sheets of paper.
 3 pill cups
 1 plastic spoon
 6 tongue depressors
 10 rubber bands (big)
 3 thumb tacks
 1 small orange ball (like a jack ball)
*Optional: It is helpful to provide scissors for each group to cut materials during the building of
catapults. However, these should be taken up before projectiles are shot to avoid the temptation
of trying to shoot scissors through the air!
Introduction/Motivation: Engineers are responsible for designing new and inventive machines
everyday. However, they are also responsible for improving an idea that has been around for
centuries to make it more applicable to today’s needs. Engineering design often involves the
creative use of components for something other than their original intent. Your team has a job to
make the most accurate catapult possible given limited materials and time. Think hard, have fun,
and good luck!
Vocabulary/definitions:
Catapult -- cat⋅a⋅pult
[kat-uh-puhlt, -poo lt]
–noun
1.
an ancient military engine for hurling stones, arrows, etc.
2.
a device for launching an airplane from the deck of a ship.
3.
British. a slingshot.
–verb (used with object)
4.
to hurl from a catapult.
5.
6.
to thrust or move quickly or suddenly: His brilliant performance in the play catapulted him
to stardom.
British.
a. to hurl (a missile) from a slingshot.
b. to hit (an object) with a missile from a slingshot.
–verb (used without object)
7.
to be catapulted.
8.
to move or spring up suddenly, quickly, or forcibly, as if by means of a catapult: The car
catapulted down the highway. When he heard the alarm he catapulted out of bed.
Origin:
1570–80; < L catapulta < Gk katapéltēs, equiv. to kata- CATA- + péltēs hurler, akin to pállein to
hurl
Related forms: cat⋅a⋅pul⋅tic, adjective
Synonyms: 5. throw, fling, propel, pitch, shoot.
Procedure:
Goal: In a two-person team, construct a mechanism that will catapult the provided projectile to
the prescribed target with the materials provided.
Design Constraints:
1. The catapult must be constructed only from the materials provided.
2. The catapult must be operated by one person with one hand.
3. The catapult must be launched from a stationary position on a table and must be selfsupporting.
4. Simply “throwing” the ball using a spoon, etc., is not a catapult. There has to be a mechanism
which projects the object.
5. You will have 30 minutes to construct your catapult.
Judging Criteria:
1. Each team will select one team member to launch the catapult.
2. Two launches will be allowed per team (time will be tight, so when your time is up, we must
move on!)
3. The launch will be scored by where the ball lands at first contact in relation to the target.
4. The judges’ decisions are final.
Attachment:
Projectiles Module Overview
Catapult Lab Report 1
Catapult Lab Report 2 longer with energy
Catapult Extensions
PS Newton’s 2nd balloon lab
Science Joywagon Projectiles
Available from Science in Motion www.amsti.org/asim
ASIM Demo Air Cannon
ASIM Demo Ballistic Cart
ASIM Lab Muzzle Velocity
ASIM DemoPop and Drop
ASIM Lab Range vs Angle
Safety issues (if applicable):
Overall this is a very safe activity without any major issues. But depending on the group of
students, you might want to do this outside, or require safety glasses if you are afraid that
someone might shoot their eye out with a rubber ball. Students should not use catapults to
project materials other than rubber balls or alternate prescribed by instructor. Thumb tacks are
extremely sharp so care should be taken when handling them. Band-aids should be on hand.
Tongue depressors (or popsicle sticks) can splinter, especially after being impaled by thumb
tacks. Students should be instructed to shoot projectiles away from their own faces, and away
from any people.
Materials tips:
Small rubber “jacks” type balls can be found at dollar stores, CVS, and Oriental Trading (but
only in bulk quantities there). Small Dixie cups (such as those used in bathroom dispensers)
work as well as pill dispenser cups. Popsicle sticks work as well as tongue depressors. Packages
of small paper “lunch” bags can be found at most grocery stores. If you do not want to deal with
bouncing solid rubber balls, you can substitute ping pong balls, cotton balls, grapes, etc.
Design tips:
Don’t give students any help with designs! Let the teams (2 students per team) brainstorm and
come up with their own designs. It is much more fun if everybody can see only their OWN
catapult until testing! Then they should see ALL of them tested for comparison and more
learning. Encourage students to use all the materials in the most efficient, effective way
possible, but do not require that all materials be used. Some students may come up with a very
simple design that works quite well only using some of the materials given. Of course no group
should get extra materials unless all groups get the same.
Troubleshooting tips:
1) Put all materials including directions and the two additional sheets of paper (brightly colored
paper makes for more interest) inside the paper bag the day before the activity. Then it is easy to
pass out one bag per pair of students, and they have more time to test their catapults. 2) Go over
the lab report (if you are having them complete that) before building, so students will know what
they need to measure and calculate ahead of time. 3) Set a time limit for designing and building
and stick to it; 30 minutes is suggested. 4) Using different sizes of rubber bands—from small to
very large—makes this activity more interesting. 5) Have multiple “contests” for catapults if
time permits. Suggested: longest horizontal distance (range), highest, most accurate (nearest the
bull’s eye on a prescribed target taped on the wall ahead of time), most precise (most able to hit
the same spot repeatedly). Give prizes—bonus points, candy, certificates, etc., for the winners.
Investigating questions:
1) What physics is used in catapults?
2) In the earliest catapult and trebuchet designs, which do you think came first—the
knowledge of physics, or the mechanical apparatus? Explain your thoughts and ideas.
3) After testing your machine, discuss concepts which are more clear to you now.
4) If you built another catapult, how would you do it differently, and why?
5) What are the connections with this activity and engineering?
Assessment:
1) Instructor observation of each team as they design, build, and test catapult for accuracy in
shooting projectile at a prescribed target taped to the wall ahead of time.
2) Lab Report along with any given extensions.
3) A rubric would be helpful. For example:
 Teamwork
5 pts
 Efficient use of materials and time 5 pts
 Design of catapult
5 pts
 Accuracy of catapult
10 pts
 Lab Report
25 pts
 ---------------------------------------------------- TOTAL
50 pts
 Comments:
Activity extensions:
Note: These extensions will add time, but are big positives for the engineering process
including problem solving, teamwork, testing, choosing optimum design and materials,
analyzing and evaluating. These are also in an attachment to print with space for writing to
print for students.
Extension A) Lesson for catapults –optional, if time permits—ask instructor!
1) After following instructions on attached page for Capstone 101 Engineering Design “The
Catapult,” and testing your design, do the following:
2) Inquiry iteration #2: Take any materials from the extra pile and improve your catapult.
This can include wire, tape, note cards, glue, thicker utensils, extra utensils. If you want
to use OTHER materials, you must get instructor approval first. List materials you are
using below:
3) EXPLAIN why you chose to use these materials to improve your catapult.
4) TEST your catapults and make a data table showing results and comparison of the two.
Extension B) After watching the video clips from Troy:
1) Explain the physics behind a trebuchet. Diagrams/sketches are great!
2) Compare and contrast this with the small catapults that you made.
3) Do you think this was an effective weapon in warfare? Why or why not?
Extension C) More with Vectors and Energy
1) You already determined horizontal, vertical, and resultant velocities for your projectile,
as well as the vertical component of the energy. Now explain how you can determine the
resultant maximum potential and kinetic energies!
2) Using your explanation above, how much elastic or spring potential energy was stored in
the material of your catapult (ignoring losses due to heat).
3) In reality, how efficient do you think this device is compared with other tools/weapons?
Research this if possible to help get evidence for your ideas. Explain how efficient this is
compared with some other systems, and WHY.
Extension D) Production
1) Design an experiment to test methods of production. Explain step by step the procedure
for your experiment. How would you analyze your results and determine the optimum
method of production? Be specific! Include a scoring guide or rubric to show how you
would make this decision.
2) What actual uses in industry might a catapult have? Brainstorm with your group and list
as many as you can come up with.
Extension E) Interdisciplinary/Cross Disciplinary
1) Work with your Social Studies instructor to research how catapults and trebuchets have
been used in the past. Include details on at least one war where they were actually used.
Create a Power Point including dates, uses, and how effective these tools were. Include
parties/countries involved, and the outcome of the war. Also include WHY the
“winning” side prevailed, and whether or not the use of these weapons was considered a
factor.
2) Work with your English instructor to write an essay on catapults or trebuchets. Include
as much information as you can about when and how they were used (see #1 above).
Your essay might include your reflections on the use of these weapons as compared with
others. If catapults were used for other purposes, include that as well.
3) Alternate assignment: Write about possible uses for catapults. Use persuasion to
try and sell catapults to a potential buyer!
4) Work with your Math instructor to design a lesson where you can use your catapult and
what you have learned to do an activity or presentation in your math class to cover or
reinforce math you will be doing in that course.
Activity scaling/differentiation:
This activity can be used for almost any level student. Accommodations can be made, including:
1) Leave out the lab report and calculations if necessary. This makes the activity quite
simple.
2) Instead of using thumb tacks, use scotch tape.
3) Project ping pong balls instead of rubber “jacks” type balls. Ping pong balls are very
light with a lot of air resistance so will not go very far nor pack a great deal of force.
Additional multimedia support:
1) SEE HUMAN CATAPULT http://www.break.com/action-sports/human-catapult.html
2) SEE CAR CATAPULT http://www.break.com/usercontent/2008/5/Car-catapult-onstreet-507171.html
3) Clips from movie—TROY—showing Trebuchets in ancient warfare
4) Computer Lab using the Physics Zone on Science Joywagon
http://www.sciencejoywagon.com/physicszone/01projectile-motion/
(See Attachments; this site costs $5 per year to use but is well worth it.)
References:
http://www.catapults.info/
http://www.knightforhire.com/catapult.htm
http://www.howstuffworks.com/question127.htm
http://www.teachengineering.org
http://www.break.com
http://Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2009.
Alternate but similar activities; these are less open-ended:
1) Catapults using cotton balls
http://teachengineering.org/view_activity.php?url=http://www.teachengineering.org/collection/c
ub_/activities/cub_mechanics/cub_mechanics_lesson04_activity1.xml
2) Catapults using grapes
http://teachengineering.org/view_activity.php?url=http://www.teachengineering.org/collection/c
ub_/activities/cub_simp_machines/cub_simp_machines_lesson04_activity1.xml