# Jack's Science Fair Project

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posted:
12/24/2012
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```							Science Fair Project
Projectile Projection
Trebuchets
Jack Tiffany
Statement of the Problem

Does the weight of the counterweight and/or projectile
affect the distance the projectile is launched?
Project Overview

I shot the projectiles while changing the weight
of the projectile and that of the
counterweight. I then recorded all of it on a
chart.
Research
    Summarize your research here in three to five bullet points:
 Trebuchets have been used since the middle ages.
 Trebuchets are more accurate than catapults.
 Trebuchets are more simple to make.
 The Trebuchet was invented in China in 300AD
Variables

 Independent variable: The weight of the counterweight and the projectile.
 Dependent variable: The distance the projectile is launched.
   Constant variables: Length of the arm, size of trebuchet, distance arm is pulled,
amount of time launched, size of basket.
 Control group: The 10 launches with my 1lb weight
Hypothesis
     Hypothesis/Prediction is the more the weight of the counterweight the
farther the projectile will go. The heavier the projectile the less far it will
go.
Materials
   20g, 40g, and 60g ball from Science Olympiads
   3 meter sticks
   A 1lb, a 2lb, a 3lb counterweight
Procedure

   1. set the counterweight to 1lb
   3. Pull back string to mark 5.
   4. Launch, measure, and record.
   5. Repeat steps 2-4 9 more times
   6. Set the counterweight to 2lbs.
   7. Repeat steps 2-4 10 times.
   8. Set the counterweight to 3lbs
   9. Repeat steps 2-4 10 times
   10. Record all the results on the chart
Data/Observations (Analyzes)

1 kg at 40 grams                            2kg at 40 gramms        rams               3 kg at 40 grams

trails                   distance           trails                  distance           trails                  distance

1               1.24                       1               1.42                       1               1.62
2               1.29                       2               1.34                       2               1.72

3               1.27                       3                1.3                       3                1.8

4               1.28                       4                1.4                       4               1.61

5               1.46                       5               1.45                       5               1.63

6               1.29                       6                1.4                       6                1.6

7               1.26                       7               1.38                       7               1.64

8               1.34                       8                1.4                       8                1.7

9               1.23                       9               1.27                       9                1.8

10                 1                       10               1.43                      10                1.5

1.266                                      1.379                                      1.662
Conclusion
The heavier the counterweight, the farther the projectile is launched.
The heavier the projectile is, the less distance the projectile is launched.
Possible Experimental Errors
 I may have launched it at mark 4 a few times.
 The string may have caught on the arm, reducing the distance.
 I may have not accurately measured the ball a few times.
Applications and Recommendations

     To improve the results, I would have run the experiment 15 times instead of 10. Also I
would have made sure to check the recoil. This could be used in real life if you were trying
to throw a basket ball and a bowling ball. You wanted to throw them to a friend and didn’t
know how much force to use.

```
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