Science Interim Assessment Task 9th Grade
Projectile Motion
The task below forms the main focus of the unit on Projectiles. Students explored some of the properties of
projectiles using different types of balls on the first day of the unit. On day 2 students were introduced to the
river gorge scenario, where they brainstorm ideas about how they could solve the problem. We decided to
use catapults as a way to approach the problem. Students were provided with a checklist to guide their
progress as well as a description of the required sections of the project. Students were required to test one
of the two variables changing arm length or angles to see how range and initial velocity are affected.
Concepts were developed during circle discussions and research from articles provided. A graphic
organizer was provided to assist with recording research summaries and bibliographic information.
Research summaries were organized into a logical and coherent two-page paper. Students practice using
protractors to measure angles by making scale diagrams which they applied while collecting data. They
were also required to apply skills and concepts from previous lessons on measurement, kinematics and
force.
Unit Project Problem
Instructions
Read the scenario below and then answer the questions below.
River Gorge Scenario
You are 6 days into a 2 week hiking trip with a group of friends near the Royal Gorge in Colorado. As you
walk along the trail you notice how steep the cliff walls are that drop down into the Gorge. You and your
friends are trying to decide how deep the gorge is (about 365 m) when you hear cries for help coming from
across the Gorge. You notice a group of hikers who appear to be stranded across the river.
They decided to cross the Gorge on a rickety old bridge that gave way just as their last group member
finished crossing. The hikers indicate to you that they have been stranded for 4 days now without any food
or water. They are dehydrated and weak, you must do something to help them! You all try your cell
phones but you have no signal. Two of your group members volunteer to hike back out of the wilderness to
alert the authorities, but you know that you must do something to help the hikers until someone can come
rescue them.
Questions: But how will you get food and water across the Gorge to them? The cliff walls are too steep to
climb down. Can you think of anyway to help them?
Modified from original resources on this website
http://www.ncsec.org/cadre2/team29_2/catapult/catapult_module.html
Science Project Checklist
Use the following checklist to rate your progress for the project. Have you:

Selected a Question for your experiment

Created a topic web

Used topic web as well as research summary to create a main research question and sub-questions

Completed research on your topic from the resources provided

Cited your source for all information collected on note taking sheets

Organized you literature review into a 2 page paper

Literature review graded by you and your peer

Develop a design plan and build your model

Created hypothesis for your experiment

Identified independent and dependent variables

Identified controls

Organized materials that you will need to collect data

Prepare procedure for collecting data

Collected data and organize them into tables

Create graph

Discuss your results

Conclusions tied to research, hypothesis and data

Recommendations for further research

Problems and mistakes
Projectile Motion
The Catapult Lab
Objective: To apply the laws of Physics and the equations for projectile motion to design a catapult that
can accurately launch a marshmallow and hit a designated target.
Requirements and Design Rules:
1) In this lab you will be building marshmallow catapults.
2) Your catapult will need to be able to launch a marshmallow in the range of 3-6 m.
3) Your catapult must be able to launch a marshmallow (large variety – approximately 4 cm X 4cm X 4
cm) at any angle between 0 and 90 degrees.
The Look

All catapults should be composed of scrap materials found that you provide I will provide the
marshmallows.

The appearance of the catapult will not be judged, but you should pay careful attention to design
elements that affect the ability of your catapult to adjust to new distances.

There are several design ideas provided on the attached sheet. You may use one of these designs or
adapt one to guide your catapult design.
Product to be submitted

You need turn in a report

You will have 2 class periods to design and build the catapult (keep this in mind so that you can
work at home if necessary).
Format for Report
You will be graded on the following items:
1) Background Research
2) Design Plan
3) Data Collection
4) Data Analysis
5) Conclusion
6) Organization and presentation of report
Select one of the following questions
•
How does changing the angle affect the initial velocity and range of the projectile?
•
How does changing the length of the arm affect the initial velocity and range of the projectile?
Your background research must include but not limited to the following:

Information about the history of catapults and how they have been used
o Projectile motions concepts
o Information about River Gorge
o Energy
o Force

Use the note taking sheets to collect information about each concept in your web.

Organize your research into a logical and coherent 2-page paper.

Include your references.
Your Design Plan Must Include:
1) A list of materials to be used (should be bulleted)
2) A diagram of your catapult.
3) A description of how you will build the catapult
4) The diagram should have all dimensions labeled (including units) and should be neatly drawn.
5) Your diagram should be drawn on plain white paper and should fill most of a single page.
Resources:
http://www.stormthecastle.com/catapult/how-to-build-a-catapult.htm
http://www.knightforhire.com/catapult.htm
http://hubpages.com/hub/thejockspot_how_to_build_a_catapult
Use the following links to find out about this gorge. Make a list of any ideas to get that could help you solve
the problem
http://www.royalgorgebridge.com/ http://www.royalgorgebridge.com/RGBP_Video/video.html
Procedure for Data Collection should include a description of:

Appropriate hypothesis related to selected question

What are the variables needed to describe projectile motion?

What data will you collect from your physical experiment?

How will you collect the data from your experiment?
Your Collection and Data Analysis may include:
1) Data table that includes time of flight(s), distance flown in horizontal direction, angle of launch, or
length of arm. You must test at least 3 different angles using 2 replicate trials for each angle. ( Your
table could look like this)
Independent
Time
Horizontal
variable
1
distance 1
Time 2
Horizontal
Average
Average
distance 2
time
Horizontal
Distance
Initial velocity
Independent Time
variable
Distance
Initial
velocity 1
Time
Distance
Initial
Average
velocity 2
initial
velocity
Data Analysis
1. A value for the average initial velocity of the marshmallow and an explanation of how initial
velocity of the marshmallow was determined. (Refer to class discussion regarding determination
of initial velocity.)
2.
a. How did changing the angle affect the characteristics of your trajectory? The initial
velocity?
OR
b. How did changing the length of the arm affect the characteristics of your trajectory? The
initial velocity?
3. What are some limitations of your physical model?
4. What are the sources of error for your experiment?
Conclusion:
Your conclusion should include an overview of your findings and describe any sources of error that might
be present. Give some examples of real life projectiles whose landing spots must be carefully predicted.
Explain the best situation for solving the river Gauge problem.
Organization and Presentation:
1) Report should be neatly typed or written and sections should be well-marked.
2) Mistakes must be either erased or corrected with white out.
3) All answers are presented in complete sentences (excluding the list of materials, which may be
bulleted).
Rubric for Catapult Laboratory Report
Outcomes
Below
Meets
Above
Standards Standards Standards
Statement of Objective: States why the student is doing the
0
2-3
4-5
0
2-3
4-5
0
1-2
3-4
0-1
2-3
4-5
0
1-2
3-4
Accuracy: Projectile hit target on testing day.
0
1
2
Organization and presentation: Report is neatly typed or written,
0
1
2
0
2-3
4-5
0
2-3
4-5
investigation and what the goals are. Should be clear and
concise. Clearly states the question and sub-questions.
Hypothesis that is being investigated. Independent and dependent
variables
Design Plan: Complete description of the catapult and diagram
with all parts labeled and clearly drawn. Description of steps used
to build the catapult. Actual; model of catapult
Data: All steps for collecting data described. All data taken
should be listed in this section. All data must have units and data
tables should be clearly labeled. Must include: time of flight,
distance in x-direction, angle of launch and initial velocity.
Data Analysis: Correct equations have been used, calculations
are correct and appropriate units are used. See laboratory sheet
for additional requirements.
Conclusion: Results are summarized and the hypothesis
addressed. Significant sources of error and suggestions for
improvements are addressed.
sections have been well marked, mistakes are either erased or
white-out.
Manipulation and measurement: Follow Safety instructions
carefully, setup and use carefully and competently laboratory
apparatus.
Background research
Information summarized on note-taking sheets. Essay organized
in logical order with appropriate grammar. Bibliographic
information on page attached.
Total: points
Physics Note Taking Sheets
 Select topics from your topic web. Examples speed, force, catapult, range, angles
 Define each term and explain how it is related to projectiles
 Use the note taking sheets to record your information
 Information must be written in your own word and source recorded to receive credit
Book
______________________________________________________________ ___________
Author name or Editor name
Date
___________________________________________________________________________
Title of the book
___________________________________
Location
_____________________________________
Publisher
What I learned from this source
Book
______________________________________________________________ ___________
Author name or Editor name
Date
___________________________________________________________________________
Title of the book
___________________________________
Location
_____________________________________
Publisher
What I learned from this source (use back of sheet for additional space):
Internet Article (not based on a print source)
______________________________________________________ ____________________
Author name
Date
___________________________________________________________________________
Title of full work
Retrieved on ___________ From _______________ Web site ________________________
Date
Name/Sponsor
URL
* Where possible print a copy of the article with URL
What I learned from this source
Internet Article (not based on a print source)
______________________________________________________ ____________________
Author name
Date
___________________________________________________________________________
Title of full work
Retrieved on ___________ From _______________ Web site ________________________
Date
Name/Sponsor
URL
* Where possible print a copy of the article with URL
What I learned from this source
Sample IA ----9th Grade
Student work
Physics
Catapult Lab Essay
Background Research
For this lab, we had to make a catapult and change either the angle or length of the catapult’s arm to
observe the effect on the projectile’s velocity, time to launch and land, and the distance the projectile
traveled. In this case the projectile was a marshmallow. What is a projectile? Well a projectile is any object
that once dropped, gravity is the only force acting on it 1. Based on what we had to do in this lab I
questioned how changing the catapult’s arm length affects the initial velocity and how it affects the range of
the projectile.
Because a hypothesis is an educated guess that is based on knowledge, I couldn’t form my
hypothesis until I did a little background research. From this research, I discovered the definition of a
projectile as stated above. I also found that the word “catapult” is used to describe a machine that hurls or
launches a projectile, for example a sling shot or cannon.2 Objects that are projectiles not only move
vertically, but horizontally. As an object move horizontally, the object continues to move downward
because gravity is the only force acting on it3. To help with the design of my catapult I found that there are
three major types of ancient catapults: the Ballista, Onsager, and the Trebuchet (which is the oldest catapult
and was invented by the Chinese). The Ballista was invented by the Greeks and the Romans.
Another type of catapult is the Shagouf, which is a long pole balanced in the middle of two poles,
with a weight on one end and a rope attached to the other end with a bucket tied to it kind of like a see-saw4.
Catapults started being used for hunting by flinging small stones, then to defend castles. Overtime, as the
castles grew bigger the catapults got larger as well, then they were used during wars. Catapults that were
built with wooden arms allowed the catapult to hurl stronger, sharper objects, and increased the speed of the
object. The mightiest catapults could hurl an object over three hundred pounds5.
1
www.physicsclassroom.com/class/vectors/u3l2d.htm
www. catapults.info/
3
www.pyhsicsclassroom.com/class/vectors/u312d.htm
4
www. catapults.info/
5
Catapults History, www.buzzle.com
2
Also, the longer it takes the catapult to rise, the less velocity the object or projectile moves at6. I also
discovered that the longer the catapult arm is, the higher the projectile’s velocityis7. The best angle to launch
a projectile is a 45-degree angle because the projectile will move halfway between a horizontal and vertical
motion. A 45 degree angle is the best angle because if a projectile is launched a 90 degree and it doesn’t
move horizontally just vertically, a 45 degree angle moves both horizontally and vertically 8.
I also found that Isaac Newton’s statement that an object in motion tends to stay in motion, also
known as inertia. Inertia plays an important part in projectile motion because it explains why an object in
moves without a source of propulsion9. Also a vector quantity is something that has both magnitude and
direction. A good example is velocity, which has both speed and direction. This is a good example because
the definition of velocity is a speed in a specific direction. After researching, I was ready to form my
hypothesis, which states that the longer the arm is in length, the less time it takes the catapult arm to rise, the
higher the projectile’s velocity and the farther its range.
Design Plan
With my hypothesis formed, I was ready to build. My materials were:
○ 20 Popsicle Sticks
○ Tape
○ A Pen/ Pencil
○ A Rubber band
○ Scissors
To build my actual Catapult we had to:
1. First we had to make the structure, which needed 12 popsicle sticks. To do this I taped two sticks
together. (Repeat this 6 times.)
2. To finish the structure or base of the catapult, I then take the popsicle sticks that I had taped
together and then taped them in the form of a pyramid.
3. The next step would be to make the catapult arm, which takes about another 5or 7 popsicle sticks
taped together then tape this into one of the bottom corners of the pyramid.
4. The last step would be to make the paper cups, which I use, a square pattern, and tape them on to
the catapult arm at different lengths. The cups should be at least 2 centimeters apart.
6
www.physicsclassroom.com/class/vectors/u3l2d.hlm
http://tuhsphysics.ttsd.k12.or.us/Research/IB05/AsaiGrafPete/index.htm#conc
8
Physics A First Course by Tom HSU,PH.D, 2008
9
www.wisegeek.com/what-is-projectile-motion.htm
7
I decided that in order to make my experiment more efficient, my partner and I would put the
cups at different lengths of the catapult arm. This way during our experimenting we wouldn’t have
to change the arm.
Picture of Model
Data Collection Procedure
1. Gather all the materials to collect our data.
2. Put the catapult at the starting line/point, which is where we put to mark the starting point or 0 meters
(0cm), then up to three meters after that.
3. Put the projectile or marshmallow on the catapults.
4. Pull down the catapult’s arm to a 45 degree angle, then release the arm.
5. Time the amount of time the projectile (marshmallow) takes to land.
6. Measure the distance the projectile traveled from the catapult to where it initially landed.
7. Record data.
8. Repeat steps 1-7 for as many cups there are (we had 4 cups).
After collecting my data, I found that the average total velocity for the marshmallow was 11.8 cm/s.
To calculate the initial velocity we set up the catapult with the arm facing the wall. We measured the length
of each cup on the arm (the arm length different). Next, we timed how long it took the marshmallow to hit
the wall. Then we used the formula D x T = V (Distance x Time = Velocity). In this case, the distance is the
length of the arm and the time is how long it took the marshmallow to hit the wall.
Charts:
Independent
Time 1
Variable/
Horizontal
Time 2
Distance 1
Horizontal
Average
Average
Distance 2
Time
Horizontal
Length of
Distance
the
Arm(Cups)
Cup 1
.47 sec.
108 cm
.47 cm
85 cm
0.705 sec.
96.5 cm
Cup 2
.37 sec.
80 cm
.53 cm
95 cm
0.45 sec.
87.5 cm
Cup 3
.41 sec.
80 cm
.41 cm
78 cm
0.41 sec.
79 cm
Cup 4
1.22
41 cm
.41 cm
64 cm
0.815 sec.
73 cm
Independent
Time 1
Distance Initial
Time 2
Distance
Initial
Average
Variable/
Velocity
Velocity
Initial
Length of
1
2
Velocity
Arm (Cups)
Cup 1
.35 sec. 45 cm
15.75cm/s .28 sec.
45 cm
12.6 cm/s
14.17cm/s
Cup 2
.25 sec.
39 cm
9.75 cm/s
.28 sec.
39 cm
10.92cm/s
10.33cm/s
Cup 3
.25 sec.
33 cm
8.25 cm/s
.34 sec.
33 cm
11.22cm/s
9.73cm/s
Cup 4
.50 sec.
27 cm
13.5 cm/s
.47 sec.
27 cm
12.69cm/s
13.1cm/s
Data Analysis
After collecting our data, we found that by changing the arm length we increased the range or
distance that the marshmallow traveled. From our data, we can conclude that the longer the arm, the farther
the marshmallow travelled. However, the longer that the arm was, the more time it took the arm to launch
the projectile. During our experimentation we found that there are few limitations to our catapult, however
our model was a challenge because you had to hold it down or weigh it down in order to launch the
marshmallow without the catapult falling backwards and breaking. The base of the catapult couldn’t support
the arm while launching the marshmallow.
There were a few sources of error when we first did our experiment. These were that we forgot to
launch the marshmallow at the best possible angle, so we weren’t getting the best results. Also we were not
measuring where the marshmallow initially landed. This was a problem because it caused inaccuracy in our
data.
Conclusion
Overall, my hypothesis was correct; that increasing the length of the catapult’s arm it did increase
the range or distance. However, the longer the arm was the more time it took the catapult arm to rise to
launch the marshmallow. I believe that the best solution to the Gorge problem, where there are stranded
starving hikers across the gorge, is to make a catapult with a arm as long as possible and to launch the
supplies over to them. Or to be more precise on the arm length, the arm should be about 164.5 meters. This
is based off the fact that my catapult arm was .45 meters or 45cm and the marshmallow traveled over a
meter (1.08 meters or 108cm). If you multiply my .45m catapult arm by the gap or the gorge, you should get
164.5 meters.
A real life situation besides the gorge problem, would be during World War Two. Soldiers used
catapults to launch grenades and gas bombs over long distances. The launch of these catapults would have
to be precise because the soldiers needed them to hit their target or opponent.
Through this project, I learned why catapults are important, as well as why and when they were used- which
was mostly in wars or in the Gorge situation to save a life.