Building a Catapult

by Stephen Alwon and Sherwin Fernandes

Introduction

Anchor Video

Concept Map

Project Calendar

Lesson Plans

Letter to Parents

Assessments

Resources

Modifications

Grant

SUMMARY

Mathematics in AISD is taught for the most part as a series of lectures disparate from everything else the students learn in their other classes.  In using a project based around designing a catapult, students will be able to see mathematics come to life in a manner that brings together physics, engineering, and history in a way that they have not seen before.  The students will participate in a series of labs during which they will construct both the basic theory of projectile motion and the basic principles and behavior of quadratic functions.  Students will then be able to put their knowledge to use by building a working catapult and rationalizing how far it will launch a ball.  Through this project, the students will be able to bring together mathematics and physics in a manner that will enable them to solve a problem that has been around for thousands of years, giving them a historical background for their project.  Additionally, the students will have a working knowledge of the basic concepts of physics, allowing them to be better prepared when they enter a physics course.  Finally, the project will be fun, and will encourage students to think deeply about mathematics because they want to, not just in order to pass a test or so they can graduate.

 

 

DESCRIPTION

The projectile launching project is primarily about applying concepts on such as forms of energy and conservation of energy, as well as acceleration due to gravity and inertia. To aid in the usage of these ideas the final lab on building a projectile launcher is precluded by several learning activities on the required topics.

To understand how energy is stored in a spring students will first measure the variation of the length of a spring with force. This will be done by hanging a spring from a stand, applying different weights to the free end and measuring the extension of the spring with a ruler. To calculate how much energy is stored in the spring, students will count energy as Newton-meters and find out how many Newton-meter boxes are under the force distance graph.

To study projectile motion students will use a stroboscope and extended exposure camera to record the path of a falling ball. Images of the parabolic path will be used to study the linear nature of the horizontal component of motion. The vertical fall will be used to study how the distance traveled is proportional to the square of time.

To predict how far the projectile will travel, students will take readings from a projectile-motion applet. Students will record how the distance traveled by a projectile will vary with the speed and angle it is launched at. The data will be combined into a 3-D curve (using a math computer tool).

To demonstrate that the energy with which the ball is launched is transferred over its flight, students will observe the conservation of energy in a falling ball. A motion detector placed below a ball will record the height and speed of the ball as it falls. These will be used to calculate the kinetic and potential energies and how they add up to the same amount throughout.

The main lab will incorporate data and concepts acquired in previous labs into the design of the projectile launcher. Students will consider the most energy and cost efficient way to transfer the projectile from the launch base to the given target. Once students have designed their launchers they will construct them using an erector set and springs. They will then predict where the ball will land using information gathered in previous labs.

When the launchers have been built and tested, each team will present their findings and discuss design and implementation aspects of their project.

RATIONALE

One of the main problems with the way mathematics is taught in AISD is that it is taught in a vacuum, with rarely any connection being made between the mathematics classroom and any other class they are taking.  Students are made to forget everything they learned during the previous hour and start entirely fresh when they enter their mathematics class.  With this project, students will bring together concepts from various subjects such as engineering, physics, and history while they are learning mathematics.  The problem of how to best launch a projectile is one that has been around for hundreds of years, and students will be able to see this problem come to life in their world history class.  The ability to bring together mathematics and history will encourage students who are interested in either subject to seek out the other.  Students will discover how wars were fought for thousands of years, making the problem of how to build a working one relevant to students who enjoy history and social studies, while students who enjoy mathematics and the sciences will be able to see the social studies in a new light.  The project will also introduce students to the engineering process, from learning the necessary physics and mathematics to designing and constructing a working catapult.

POTENTIAL IMPACT

 

Our project will attempt to get students interested in mathematics by bringing other disciplines into the mathematics classroom.  In this way, students will be able to see how mathematics can relate to subjects they most likely will not have seen a connection to before, such as history.  Students will be motivated to learn the mathematics not necessarily just to learn math, pass a test, or graduate high school, but as a way to better understand how history was shaped for hundreds of years.  Students whose primary scholastic interests were in social studies before participating in the project will have a different outlook on mathematics and the ways it can be used.  In this way, these students will have a new appreciation for mathematics and will be more excited to participate in math classes in the future.  Conversely, students whose main interests lie in the sciences will have a new outlook on history, and will be more excited to participate in those classes.  Our project will also prepare students for when they take physics by introducing them to some of the more basic concepts they will learn in that class.  This will enable the teacher who has these students to save time in covering some of the basic concepts, and instead allow them to spend more time on the concepts that the students have not been presented previously.

EVALUATION PLAN

 

Our project will depend on two main techniques for measuring the progress of our students.  The first will be the labs and homeworks which will be assigned on a regular basis.  The labs will be done mostly in class, with the students able to finish outside if necessary.  Through these, the students will be able to witness first hand the physical and mathematical concepts they are to learn, and successful completion of the lab write-ups will depend on them thoroughly understanding the concepts the labs are designed to exhibit.  These will let us know that the students are working during class time and that their work is productive.  The homeworks will be designed to evaluate the concepts that are more mathematical in nature – problems such as finding quadratic roots.  These will enable us to quickly judge if the students are “getting” the mathematical concepts involved in the project.  The other evaluation technique will be through the final project itself – each group’s design of the catapult and their rationale of why their catapult works and how far they expect it to shoot.  This will allow us to determine how well the students brought together all of the concepts involved and how well they are able to communicate their knowledge of those concepts.

 

 

 

 

 

 

 

 

 

 

 

 

 

PROJECT CALENDAR

 

 

Monday

Tuesday

Wednesday

Thursday

Friday

Week 1

Anchor Video Discussion: what is force?

Linear Relationships: students explore how spring extension varies with force.

Mapping projectile motion using a stroboscope.

Looking at the horizontal component of the motion diagram. Using Linear regression to graph.

Linear relationships

Y=mx+b.

(y-y1)=m(x-x1)

Week 2

Looking at the y component of the projectile diagram

Quadratic relationships. Examine how the Area of a square is proportional to the square of the side length.

Graphing quadratics from data and equations.

Finding quadratic roots: factoring

Finding quadratic roots: quadratic formula

Week 3

Fitting data to a linear or quadratic equation

Cannon firing applet: what is the best angle to fire at?

Similar triangle exploration: how are angles related?

Comparing the ratio of side lengths with angle. Plot on graph to get sin, cosine, and tangent.

SOH, CAH TOA,

Week 4

Basic physics: force, conservation of energy

Potential/ kinetic energy exploration

Conservation of energy between kinetic and potential energy

Measure kinetic and potential energy of a falling ball.

Firing a projectile: ramps or catapults?

Week 5

Describe project, get in groups and work on designs.

Students continue working on designs.

Students estimate how far the launcher will fire, based on their design.

Students start building when the design is approved.

Build, test

Week 6

Initial test is run when the prototype is complete. Results are discussed within the group and modifications are proposed

Students continue building and making improvements.

Final build day, and testing in class

Presentations

Presentations

 

BUDGET

 

Description

Unit Price

Quantity

Total

Stroboscope & Tachometer, Measures RPM, Non Digital Display High Impact Case

$149.00

1

$149.00

Sony DSC-P93 5.1 MegaPixel Digital Camera – extended exposure

$317.99

1

$317.99

Erector Set 100 piece bucket

$20.00

10

$200.00

TI-83+ Graphing Calculators

$99.99

10

$999.90

Vernier Motion Detector and cable

$74.00

10

$740.00

 

 

 

 

Total

 

 

$2406.89