CATAPULT: A SIMPLE MACHINE "A mini-weapon of mass destruction"

Materials: 9 pop cycle sticks 7 rubber bands 4 clothes pins 3 small (not mini) clips 1 plastic spoon Masking tape Ammunition…marshmallows OR paint balls (should be soaked a few minutes in water to soften)

Procedures & questions (Day 1)

1. Build the catapult shown above (there is a how-to on Youtube).

2. Get the approximate weight of your ammo (paintballs).

3. Test your catapult. Keep a data log of every shot. Track the distance, time it takes to hit the ground and calculate the momentum. (Hint velocity = speed/time)

(Sample log) Distance Traveled Time Momentum Trial (meters) (seconds) () # 1

2

Etc …

4. What is the average distance your ammo travels, the longest, shortest?

1 5. What was the longest time it took to hit the ground?

6. What was your ammo’s highest momentum?

7. Study your catapult. What simple machines are found in a catapult?

DESIGN CHALLENGE (Day 2)

1. Modify your catapult to improve the distance it will shoot the ammo. You must use the spoon, but you can modify the rest of it…supply your own materials. Remember to return any parts you don't want from the original to the teacher.

2. Write down all of your modifications. You may draw a picture of it or provide a picture.

3. Predict how you think your new design will improve your shooting distance.

4. Use your now modified catapult and keep a data log of every shot. Track the distance, time and momentum.

(Sample log) Distance Traveled Time Momentum Trial (meters) (seconds) () # 1

2

Etc …

5. Compare your modified catapult to the mini-weapon of destruction design. Which one performed better? In what ways did it perform better or worse? Did you add any more "machines" that improved mechanical advantage? If your modified design performed worse than the mini-weapon of destruction, then explain what you think the design flaws were. Suggest ways to fix your design problems and other factors that influenced the results.

Write your conclusion as a paragraph.

CLEAN UP

Return any re-usable parts to the teacher.

2 CATAPULT LAB

STUDENT NAME:______PER. _____

Day 1

3. Distance Traveled Time Momentum Trial (meters) (seconds) () # 1

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Etc …

Answers to questions:

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4. Distance Traveled Time Momentum Trial (meters) (seconds) () # 1

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Etc …

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