How to Build a Tennis Ball Trebuchet?

Looking for a fun science project? Why not try building a tennis ball trebuchet? In this blog post, we’ll show you how to do it step by step.


Building a working model of a trebuchet is a great way to learn about engineering, leverage, and physics. Trebuchets were used in medieval times to siege castles and fortifications. By using a long lever arm and a counterweight, they could hurl large rocks or burning objects over long distances.

In this project, you will build a small-scale trebuchet out of popsicle sticks, hot glue, and other materials. Once it is complete, you will be able to test it out by launching tennis balls!

What is a trebuchet?

A trebuchet is a type of siege engine used in the Middle Ages. It is sometimes called a counterweight trebuchet or a gravity trebuchet. A trebuchet uses the force of gravity to hurl objects. It consists of a long arm with a bucket or sling at one end and a weight at the other. The arm is rotated and the weight falls, pulling on the arm and hurling the object in the bucket or sling.

Trebuchets were used to hurl stones, rocks, incendiary devices, or other projectiles at castles or other fortifications during sieges. They were also used to hurl much lighter objects, such as tennis balls, over obstacles in field battles.

Trebuchets were very effective siege engines and were used extensively during the Middle Ages. They fell out of use after the invention of gunpowder and cannons.

Materials needed

-Tennis ball
-2×4 lumber
-1/2 inch PVC pipe
-PVCpipe cutter or saw
-1/4 inch drill bit
-3/4 inch drill bit
-Nails or screws
-Ruler or tape measure

Step-by-step guide

A trebuchet is a siege engine that was used in the Middle Ages. It is a type of machine that uses gravitational potential energy to throw or hurl objects at a high speed. The word “trebuchet” comes from the French word for “to throw”.

Trebuchets were used to hurl large rocks, stones, or other projectiles at enemy castles or fortifications. They were also used to launched infected animals or human corpses into enemy camps in order to spread diseases.

Trebuchets were very effective siege weapons and played a significant role in the fall of many castles during the Middle Ages.

Building a tennis ball trebuchet is a great way to learn about the physics of motion and engineering. This project can be completed in an afternoon with some basic materials that can be found around the house.

What You’ll Need:
-1 tennis ball
-1 empty plastic water bottle
-Masking tape
-Paper towel roll or PVC pipe (optional)
-Pencil or pen
-Ruler or measuring tape (optional) Step 1: Cut the top off of the water bottle using scissors. This will be the launching cup for your trebuchet.

Step 2: Make two small holes near the base of the water bottle, on opposite sides. These holes will be for the trigger string. The distance between the holes should be about 1 inch (2.5 cm).

Step 3: Cut a small hole in the center of the tennis ball. This hole should be big enough for your paper towel roll or PVC pipe to fit through snugly. If you are using a paper towel roll, make sure to cut it so it is slightly shorter than the length of your water bottle.

Step 4: Thread one end of your trigger string through one of the holes you made in Step 2 and tie it off so it is secure. Make sure that there is some slack in the string so that you can pull on it easily later on. Step 5: Place your paper towel roll or PVC pipe through the hole you made in Step 3 and insert it into the opening at the top of your water bottle until it is seated firmly at the bottom.

Step 6: Tape your paper towel roll or PVC pipe in place so that it doesn’t fall out when you are ready to launch your projectile.

Step 7: Cut another piece of string and thread it through the other hole you made in Step 2 . This string will be used to swing your arm down and release your projectile . Step 8: Test your trebuchet by pulling on the release string until your arm swings down and launches your tennis ball!


Now that you know how to build a tennis ball trebuchet, you can start working on perfecting your accuracy. With a little practice, you’ll be able to hit targets from all sorts of angles and distances. Who knows, maybe you’ll even become a pro at this ancient siege weapon!

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