# 13 Nov. Sci 7 Testing motion device; Beginning Summative Project

Today we will complete, test, and modify your catapults

On the testing (today or Wednesday). You will have a distance and a target. We will measure the distance of first contact to the closest edge of the target. During the official trials you get two tries. When you launch, describe the operation of your device. Use correct motion concepts. Describe how you tested the device and your reasoning in the original construction and in the modifications.

Observe every launch of every device. Take note of the diversity of designs and how your classmates describe, build, operate, think and reason.

CONSTRUCTING, OPERATING, INVESTIGATING A MOTION DEVICE

Design a catapult that can launch a clay ball into a 0.5m x 0.5m square from at least 3m away.

• Supplies available in the Makerspace
• Other materials with permission
• Clay for projectiles
• Digital balance
• Measuring tape / meter sticks
• With your partner discuss theories on how a catapult works (note it may not employ a slingshot).
• With your partner, design a catapult that you can make from materials in the Makerspace (you will have one period for construction and trials).Plan an experiment to gather data about how far clay balls of different masses (you will be given a mass range to work within) can be launched by your catapult. You will need to have a data table to record your results.
• Explain how you will test and trial your catapult. What data will you gather? How will you record it?
• Construct your catapult with your partner and and begin testing it. How can you improve the initial design? Once you have tested it do you need to make changes to the design? Can you make it more accurate or shoot farther?
• Take picture of the designing and building process
• Once everyone has finished construction each team will get two chances to land a clay ball into the square from at least 3m away. You will need to use your trial data to determine where you will place the catapult so that the ball lands in the square. A digital balance will be available to determine the mass of the various clay balls you trial and the one you are given during the competition.
• You will have one class period to design and build the catapult. Trials will be during the next class period. All catapults will be stored in the classroom to keep them safe.

As you work with your catapult think of how the following concepts apply:

• Distance
• Time

• Speed

• Velocity

• Inertia (Newton’s 1st Law)

• Acceleration

• Force (Newton’s 2nd Law)

• Contact and non-contact forces

• Equal and opposite forces (Newton’s 3rd Law)

• Momentum and conservation of momentum

• How could you describe the action of the catapult, the results of systematic trials, and the relevance of ideas about motion (see list above) in a poster that uses no words and now numerals–a totally visual explanation?
• EVERYTHING IS DUE AT THE END OF CLASS ON FRIDAY 17 NOVEMBER
• ### PRODUCT:    Design a (physical) poster (using no words and no numerals) that shows:

1. What you consider to be a typical catapult launch and flight of the projectile.
2. The results from your tests of the parameters of performance.
3. How you tried to hit the target (your thinking and calibrating).
4. How Newton’s 3 Laws of Motion apply. Consider BOTH the catapult and the projectile. (Think carefully about when the speed/velocity is changing and when it is constant. Think about where forces appear in the launch and flight and identify the paired 3rd law forces).
5. How the principle of the Conservation of Momentum applies.