MARSHMALLOW CATAPULT-LIKE DEVICE PROJECT

You may work with ONE PARTNER or ALONE. No exceptions. THE MAXIMUM “GROUP” SIZE IS 2 PEOPLE!

This project will count as a 200-point test grade and has the following parts:

Part 1: INTRODUCTION PAPER / PROPOSAL(50 points)

Due date: ______

At least 2 good paragraphs. Handwritten only. (NO exceptions. I don’t care how much you hate

writing or how bad you think your handwriting is. HANDWRITTEN ONLY!)

Must include discussion of all of the following. Order is up to you.

-- what is a catapult? What is the traditional use of a catapult?

-- earliest known (time period, design basics)? when in greatest use?

-- traditional materials for construction and projectile? (NOT model materials!)

-- types of catapult-like devices (brief description and who used them)

-- your design (MUST INCLUDE BASIC DIAGRAM LABELED FOR MY REFERENCE)

-- type of simple machine (be specific & explain your reasoning)

-- any other simple machines that will be part of the design

-- materials you plan to use

** must include at least 5 good sources. Not sure if they’re good? ASK!

** all sources must be cited correctly using MLA format and a complete bibliography must be

attached to your paper. No bibliography? NO CREDIT. AT ALL. END OF DISCUSSION.

Part 2: CATAPULT-LIKE DEVICE (50 points)

Due date: ______

Your device must meet the following specifications:

a. maximum allowed mass is 200 g

b. maximum allowed height is 18 cm

c. maximum allowed length is 24 cm

d. maximum allowed width is 14 cm

Your device MUST BE HAND-MADE. USING A KIT OR A PURCHASED CATAPULT WILL RESULT IN A

0 FOR THE ENTIRE PROJECT (because this is cheating).

* Acceptable materials include... rubber bands, plastic spoons, pencils, cardboard,

toothpicks, popsicle sticks, straws, string, wire, screws, washers, tape, wax, glue, &

thread.

* Other materials are possible, but be sure you get them approved prior to

construction!

Your name(s) and class period must be clearly labeled on the device.

BE SURE YOU TEST AND ADJUST YOUR DEVICE BEFORE BRINGING IT TO SCHOOL!

Meeting construction requirements will get you a passing grade. The remaining points may be

awarded for creative designing, high accuracy of catapult, or extra distance.

Part 3: CALCULATIONS & CONCLUSION REPORT(100 points)

Due date: ______

** sections:

** DATA GATHERED IN CLASS (fill in data table provided)

-- launch angle (from horizontal)

-- angle through which catapult moves

-- time marshmallow is in the air

-- horizontal distance marshmallow travels

-- length of throwing arm

-- mass of marshmallow

** CALCULATIONS (fill in data table provided)

kinematics:

-- based on the time in the air and horizontal distance traveled, calculate the

horizontal velocity (use v = d/t)

-- use trig ratios, your launch angle, and your horizontal velocity to figure out the

initial velocity and initial vertical velocity. Use the diagram below to help you.

launch angleHYP

initial velocity initial vertical velocity

OPP

horizontal velocity

ADJ

-- determine the maximum height the marshmallow could have reached, assuming

vo = 0. Use d = (1/2)at2, where t = half your average time.

Newton’s laws:

-- determine weight of marshmallow

circular motion:

-- based on calculated initial overall velocity and the length of the catapult arm

(that's the radius), determine centripetal acceleration

-- find the centripetal force

-- determine arc length using the angle through which catapult moves and the length

of catapult arm (radius): arc length = (angle/360)(2*pi*radius)

-- based on arc length and initial velocity, determine time of launch. Use v = d/t

work, power, & energy:

-- use mass and initial vertical and horizontal velocities to determine the vertical and

horizontal kinetic energies

-- use mass and maximum height to determine potential energy

momentum:

-- determine momentum at launch using overall initial velocity

-- based on momentum and time of launch calculated before, determine force (using impulse = momentum at launch)

torque:

-- use the force you calculated from the momentum section and the length of

catapult arm to determine torque

** DISCUSSION

-- if you had used a steel ball instead of a marshmallow, would the projectile’s motion

have been affected (assuming we had no air resistance)? Why? What about for a

real-world situation where there is air resistance?

-- explain why the object started on a straight-line path and why it ended up in a parabola

-- what is the vertical net force while the object is in the air? Why?

-- what is the horizontal net force while the object is in the air? Why?

-- does the object have kinetic energy at the top of the arc? WHY?

** CONCLUSIONS

-- discuss sources of error (at least 3, and explain how they may have affected results)

-- discuss modifications you would make to your catapult, or if none, specific reasons it

worked as well as it did. Had you modified it prior to class? Had you built one

before? etc.

NAME(S): ______Period: 1 2 3 4 5 6 7

______

Rubric

PROPOSAL: Clarity, organization, grammar_____of 10

History & background content_____of 20

Design explanation and sketch_____of 10

Works cited correctly & clearly, with good sources chosen_____ of 10

TOTAL: _____ of 50

CATAPULT: Meets size criteria_____ of 20

Uses approved materials_____ of 10

Name / class period labeled_____ of 10

Additional accuracy or distance_____ of 10

TOTAL: _____ of 50

REPORT: Data table with info gathered in class clearly labeled_____ of 10

Calculations correct_____ of 20

Data table complete and neat_____ of 20

Discussion questions clearly explained_____ of 20

Conclusion paragraphs clear and complete_____ of 20

Discussion / Conclusion organization & grammar_____ of 10

TOTAL: _____ of 100

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Read and sign this section. I will come around and initial to acknowledge that I saw your signature.

I understand the requirements for the project, including the requirement that the catapult be completely homemade and not in any way from a kit or pre-assembled model or toy.

I promise to make every effort to be in class on the catapult lab days because I understand that the data collection is key to the remainder of the project and it will be difficult to make up.

I understand that missing the data-collection day WILL NOT get me extra days to finish the project. It will be due the same day as everyone else’s.

Signature(s): ______

Ms. Neal’s initials: ______

Data and Calculations

angle of launch
angle through which catapult moves
time marshmallow is in the air / Trial 1
Trial 2
Trial 3
Average
horizontal distance marshmallow travels / Trial 1
Trial 2
Trial 3
Average
length of throwing arm
mass of marshmallow
topic / calculation to complete / Equation you're using / Data you're using (variable AND VALUES, please!) / Your answer (WITH UNITS)
Kinematics / horizontal velocity
initial velocity (overall)
initial vertical velocity
maximum height
Newton’s Laws / weight of marshmallow
Circular motion / centripetal acceleration
centripetal force
arc length
time of launch
Work, Power, & Energy / horizontal initial kinetic energy
vertical initial kinetic energy
potential energy at maximum height
Momentum & Impulse / momentum at launch
force used in launch
Torque / torque on catapult arm