1. Title: Bombs Away! A Ping Pong Catapult
By: Hunter Lash

2. Experimental Design
Problem- What is the effect of the length of the catapult on the distance the ping pong ball travels ?
IV: Length of the catapult arm
Levels of the IV
30cm (Control),35cm, and 40cm
DV: Distance the ball travels

3. Experimental Design
Constants (3) : same ball, catapult, and testing environment
Hypothesis: If the length of the catapult arm is 40cm, then distance the ping pong ball travels will be further than the 30cm or 35 cm arms.

4. Materials
3 boards of of wood (length 29 cm), 8 boards of wood (length 12 cm), 1 board (length 7cm), and 1 board (length 34 cm)
Wood screws
3 large rubber bands
4 eye hooks
Cardboard
1 metal bar
5 ping pong balls
3 m tape measure

5. Procedures 1. Gather materials. 2. Build catapult and cradle.
3. Set arm length to 30cm.
4. Put ball in cradle and pull it back all the way.
5. Release the arm, measure and record the distance the ball travels.
6. Repeat for a total of 5 trials.
7. Repeat steps 3-6 for 35cm and 40cm arm.
8. Record and compare all data

6. Data Table Length of catapult arm (cm) Trial 1 2 3 4 5 30 1.16 1.52
Averages 30
1.16
1.52
1.46
1.55
1.26
1.39 35
1.56
1.94
1.54
1.79
1.67 40
1.73
2.02
1.63
2.14
1.81
Distance (m)

7. Graph (Trials)
Distance
(m)

8. Graph (Averages)
Distance
(m)
Length of Arms (cm)

9. Trial Outliers (Edited and inserted quickly)
30 cm Length of Catapult Mean (1.39 cm)
Trial 1 (1.16 cm) – first trail of experiment, didn’t pull catapult all the way back
Trial 4 (1.55 cm) – gust of wind blew in the window
35 cm Length of Catapult Mean (1..67 cm)
Trials 2 & 5 (194 / 179 cm) – catapult length increased as it was moving forward
Trials 1, 3, and 4 (1.56 / 1.54 / 1.55 cm) – were done correctly, resulting in more accurate distances
40 cm Length of Catapult Mean (1.81 cm)
Trial 4 (1.52 cm) – elastic band broke as catapult was moving forward
Trial 5 (2.14 cm) – changed elastic band to a slightly smaller size

10. Discussion –
Average Distances for various catapult arms were 40 cm (1.81 m), 35 cm (1.67 m),
and 30 cm (1.39 m).
Analysis: As the length of the arm of the catapult increased, the distance the ping pong ball traveled also increased (directly proportional)

11. Conclusion
The hypothesis was accepted because the longest arm (40 cm) made the ping pong ball travel the furthest.

12. Conclusion (cont) Errors made included: None If done differently:
Used a bigger catapult
Tested a heavier ball
Used a different number of rubber bands

13. Conclusion (cont)
Overall, this science experiment was a success, because I had a good time building the catapult and doing the experiment.

14. Questions
Are there any questions?