The science of ballistics involves the motion of projectiles. Exterior ballistics concerns the projectile after it leaves the device that it is shot from. The term "ballistics" comes from the name of one kind of catapult, the ballista.

- Identify the Problem
- Write a synopsis of the problem in your engineer's notebook such that you could finish this challenge without further reference to this web site.
- Be sure and include all criteria and constraints.
- Ask questions as needed to clarify these directions.
- Generate Concepts
- Research the topic, document your findings in your engineer's notebook.
- Sketch ideas in your notebook.
- Sketch an improved version of your best idea on a separate paper.
- Combine your sketches with those of the other members of your team and use a decision matrix to choose a design to develop further.
- Develop a Solution
- Create a set of working drawings in your notebook in sufficient detail that a third party could recreate your chosen design based solely on what you have in your notebook.
- Construct and Test a Prototype
- Construct a device from scrap material that will throw a marshmallow at least 10 feet.
- Shoot six times at an elevation angle of 45°, measuring the distance and time of flight for each shot. Use this information to estimate the intitial velocity.
- Based on this initial velocity, predict the range at 30° and 60°.
- Shoot six times each at 30° and 60° to check your prediction.
- Demonstrate the performance of your device by shooting three times at a one foot diameter target from at least 10 feet away, without any practice shots. Your score will be based on the total distance from the target for your three shots.
- Evaluate the Solution
- Calculate the median, mean, mode, and standard deviation of each data set.
- In your engineer's notebook, compare your results to others in the class and explain why your device did better or worse than others.
- Present the Soltution
- Document each step in the design process in your own engineer's notebook
- Present your engineer's notebook for grading
- Do the problems on GUESS paper.

- Teams of 2 or 3.
- Energy to throw the marshmallow must come from energy stored in rubber bands or weights.
- No more than 24" in any dimension.
- Must shoot at different angles (at least 30°, 45°, and 60°) at the same initial velocity
- The range at 45° must be at least 10 feet.
- Cannot practice at the target.

Evaluated using the usual rubric. Make sure you:

- Have numbered each page sequentially (outside top). If not, do it!
- Fill each page on a continual bases without large blank areas. "A page a day" is not the system here.
- Glue or staple in all inserted items.
- Sign the bottom of each page when full. Date each signature (the date of the entry is not sufficient).
- Date each entry.
- Obtain at least one witness signature. This signature should be dated (the date of the entry is not sufficient).
- Sketch your device. Do your calculations in the notebook. Annotate the sketches and calculation so that you will be able to figure them out in a year or two.
- Document every step in the design process. Clearly explain how your design was supposed to work.
- Document the results of each data run. When you encounter problems, as you surely will, write down your ideas to fix them.
- Write down everything that you do as you do it so that the information in your notebook is proportional to the amount of time spent on this project.

The device will be judged based on the quality of construction and the design elements that let it shoot a marshmallow a consistent and repeatable distance.

5 points each for:

- Computing the intitial velocity at 45°
- Predicting the range at 30° and 60°
- Shooting at 30° and 60°
- Calculating the median, mean, mode, and standard deviation of each data set.

Your score is 20 points minus your total distance away from the target in feet.

4 points per problem. Make sure and:

- List the given and unknown quatities as symbol=number unit.
- Show each equation.
- Substitute numbers and units for symbols in the equations.
- Solve each equation for the desired quantities.
- Carry units throughout.
- Box final answers together.

- A skydiver jumps from 10,000 ft. How fast is she going after:

a. 1 second?

b. 2 seconds?

c. 10 seconds?

d. What is her altitude after 10 seconds?

- A baseball is thrown straight up at 64.4 ft/sec.

a. How long does it take to get to its highest point?

b. How high does it go?

c. How long does it take to get back to your glove?

d. How fast is it going when you catch it?

- A projectile is thrown at 100 ft/sec at an elevation angle of 45°.

a. What is the speed in the horizontal (X) direction?

b. What is the speed in the vertical (Y) direction?

c. What is the time of flight?

d. What is the maximum altitude?

e. How far does it go?

- A projectile is thrown at 100 ft/sec at an elevation angle of 30°.

a. What is the speed in the horizontal (X) direction?

b. What is the speed in the vertical (Y) direction?

c. What is the time of flight?

d. What is the maximum altitude?

e. How far does it go?

- A projectile is thrown at 100 ft/sec at an elevation angle of 60°.

a. What is the speed in the horizontal (X) direction?

b. What is the speed in the vertical (Y) direction?

c. What is the time of flight?

d. What is the maximum altitude?

e. How far does it go?

Bonus: Which of the last three went farthest? Why don't hit baseballs fly the farthest at this angle?

- A projectile thrown at 30° goes 150 yards in 4 seconds

a. What is the velocity in the horizontal (X) direction in ft/sec?

b. What is the Initial Velocity?

c. How high did the projectile go?

d. How far would it go if thrown at 45° at the same initial velocity?

e. How far would it go it thrown at 60° at the same initial velocity?

Fat Brain Catapult Kit

Steve Spangler Science

The Grommet

Leonardo Da Vinci

Don't try this

And really don't try this

Or even this

And definitely not this