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
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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
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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
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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
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Trebuchet from Science Olympiads
20g, 40g, and 60g ball from Science Olympiads
3 meter sticks
A 1lb, a 2lb, a 3lb counterweight
Procedure
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1. set the counterweight to 1lb
2. Load the 40g ball into the basket
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
trails
distance
2kg at 40 gramms
rams
3 kg at 40 grams
trails
distance
trails
distance
1
2
1.24
1.29
1
2
1.42
1.34
1
2
1.62
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
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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.