PHYSICS 103

Parachuting in Sewanee

The parachute design will be "free form", meaning you can pick the materials/shapes/etc you want, except fpr the following overall limits:

Total Mass Maximum: 100 grams

This Total Mass INCLUDES these 2 REQUIRED items:

-Small "shot" Plastic Cup and

-Ping-Pong Ball

Objective: to design an apparatus that, when dropped, will have the maximum time in the air. The time to land tf must be less than 10 seconds (getting stuck on a tree or wall would disqualify it!). To qualify, it must also land with the ball staying inside the cup, and within the designated landing area.

Score = tf *100 if tf <=10 seconds (for example a time to land of tf = 2.5 seconds will give you 250 points).

Score = 0 if tf > 10 seconds

Your final score is the average score of 3 trials.

Each team chooses a "timekeeper", and all "delegates" must agree on the best estimate of each team's time to land tf on qualifying drops.

Considerations:

An object in free fall may reach a constant terminal velocity vt,when the downward directed force of gravity is equal to the upward directed drag force.

vt =[ 2mg / dACd ] 1/2

where m = mass

g = gravitational acceleration

d = density of air

A = cross sectional area

Cd = drag coefficient

The competition will be held next week at a time to be announced, launching from the WL courtyard.

Brainstorming

Select one person as recorder, and one as moderator.

The recorder will keep track off all of the ideas suggested. S/he will record on a board during the class time, but save a record of the notes for your report.

The moderator will keep things flowing and attempt to enforce the rules.

RULES

Get everybody's name and email address.

Try not to pass judgment ideas during the brainstorming session itself. Do not point out why something will not work, or is not as good as another idea. All ideas are potentially good so do not judge them until after the session. Avoid discussing ideas at this stage, which includes not criticizing and not complimenting ideas.

Write down all of the ideas. At this point of the process, there are no bad ideas. The more ideas there are at the end of a session, the greater the probability of one of them being a really good idea, or leading to one.

Try to build and expand on the ideas of others to see where it might take you. Let other people's ideas be an inspiration for your own.

Explore the parameters of the known equations.

Encourage everybody to participate. Every person has a valid viewpoint and a unique perspective on the situation and solution. In a brainstorming session you can always put forward ideas purely to spark off other people and not just as a final solution.

Each idea presented belongs to the group, not to the person stating it. You are not in competition with each other. It is the group's responsibility and an indication of its ability to brainstorm if all participants feel able to contribute freely and confidently.

Construction

You will be given time in class to construct a model that incorporates your design goals. Usually the process would involve constructing a prototype model, testing that, and then producing improved models, and repeating as necessary. Testing/design outside of class time might be required.

Report (due a week after the competition, one per team)

This exercise has a simple report.

1. Must include a list of everybody in the group.

2. Include a description of the brainstorming session including the ideas recorded at that time.

3. Describe how you chose your final design.

4. Describe your construction process. You should include a drawing of your apparatus.

5. Include your final drop time and overall score.

6. Indicate how you would improve your design based on the experience gained.