How to Design a Catapult Launcher for Physics With Ping Pong Balls

A ping pong ball's light weight makes it a safe projectile to use.

It's believed that the first catapults were used for warfare in the 3rd century. These early catapults were built by Phillip of Macedonia's engineers and used two arms, tightly wound ropes and a cord to help throw deadly projectiles. Designing a catapult for your physics class is a great way to learn about ancient warfare and stored energy. A catapult uses three forms of energy storage: tension, torsion and gravity.

Things You'll Need

• Wood block, 2 inches wide by 6 inches long
• Wood glue
• Clothespin
• Wood block, 1 inch wide by 1 inch long by 2 inches thick
• Popsicle stick
• Bottle cap
• Ping pong ball

Instructions

1. Lay the longer wooden block on a flat surface. One of the 2-inch wide faces should be facing up.

2. Glue the clothespin lengthwise to the center of the block. Allow the glue to set for 5 minutes.

3. Glue the small wooden block to the open end of the clothespin. Allow the glue to set for five minutes.

4. Glue one end of the Popsicle stick to the center of the small wood block. Allow the glue to set for five minutes.

5. Glue the top of the bottle cap to the end of the Popsicle stick that is not glued to the block. Leave about a half-inch of space between the end of the Popsicle stick and the bottle cap. Allow the glue to set for five minutes.

6. Place the ping pong ball inside the bottle cap, pull down on the end of the Popsicle stick and let go. The ping pong ball will go flying through the air.

References

• Knight for Hire: Catapults
• Real World Physics Problems: Catapult Physics
• Medieval Castle Siege Weapons: History of Catapult