Catapult Our Journey Through Making A Successful Catapult

Background Information

We wanted to use:

  • Thirty feet of PVC pipes
  • Six 90 degree elbows
  • Five T-connectors
  • Fifteen big rubber bands OR two bungee cords

We researched and watched many videos, but what stood out to us the most was this specific video:

After doing our research we came up with the idea of using rubber bands instead of bungee cords. We thought that by using rubber bands it would make the object we launch, go faster and further.

Here is a sketch of the design we created after researching:

Our Final Design

For our final design we used the following:

  • 12 feet of PVC
  • Six 90 degree elbows
  • Five T-connectors
  • Eight big rubber bands
  • One little 2x2 cup

Here is a picture of the final product:

Data Collected After The Launch

After our first few launches, the catapult did great and we didn't need to make any changes to it.


  • Reading 1- 18 feet
  • Reading 2- 20 feet
  • Reading 3- 25 feet
  • Reading 4- 25 feet

Max Height:

  • Reading 1- 6 feet
  • Reading 2- 7 feet
  • Reading 3- 4 feet
  • Reading 4- 3 feet

Questions Answered After Launch

1. Is your catapult launching consistently every time?

The range of our catapult is close to the same every time, but the maximum height is all over the place.

2. What can you change to make the launch consistent?

To make the launches consistent I will need to make sure that I pull it back in the same spot every time.

3. What revisions can you make to your catapult to get a launch that goes farther?

In order to make the ball go farther, we can add more rubber bands to make the launcher go faster and create more tension.

4. Where do you need to place your target in order to hit a bullseye every time?

In order to hit a bullseye every time, we will need to put the catapult at about 25 feet and 3 inches.

Our Equation

The formula for our equation is: y=a(x-h)²+k

Our equation is: y=-0.0413(x-11)²+5

Our Graph

Final Questions

1. When does your projectile hit the ground according to the equation you found?

The projectile hits the ground 22 feet.

2. What is the maximum height of the ball?

The maximum height of the ball is 7 feet.

3. What height is your projectile at when is has travelled 6 feet?

The height of the ball when it has travelled 6 feet is 6.0325.

4. How could you make the maximum height higher and what effect would it have on that path of the projectile?

To make the ball go higher, we can pull the lever back further to spring the ball and make it go higher.

Created by: Haley Murphy

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