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Difficulty Rating: ★★☆☆☆
Parental supervision not required, but recommended.
Introduction
Introduction
Imagine being able to launch an item hundreds of feet and predict where it will land. This is all possible with the invention of the catapult! It’s crazy how this man made structure is able to do this incredible feat. Are you interested in being able to build a similar structure but on a smaller scale?
Well, you’re in luck! Today, we are going to make a catapult at home using popsicle sticks and your favorite candy treats!
Background
Background
There are many types of catapults, but they all share the same end goal: to hurl an object through the air. Here are some types of catapults and how they work:
A ballista resembles a traditional crossbow where the force is generated by twisting the rope. Doing so would fling a spear/object when the taut rope was cut.
A mangonel resembles a transition between the ballista and the traditional catapult. This catapult uses torsion (tension around the axis) in ropes, so when the rope is cut, the object will be thrown.
The basic structure of a trebuchet is a lever with the shorter arm facing the enemy. A weight is then applied to the shorter arm which adds force for the object to be released.
Now we can go over a quick summary of the PHYSICS of catapults. The physics of catapults is using stored energy, also known as elastic energy, to hurl objects without an explosion. The three primary energy storage mechanisms are tension, torsion, and gravity. An example of tension and torsion is when a rope is tight or tightly wound and you can see this very commonly in the ballista and mangonel catapult. This stored energy is converted into kinetic energy (the energy of motion) when the rope of the catapult is cut or a force is applied which allows the object to be thrown to far distances.
Now that we know more information about the physics of catapults, we can get started on the experiment!
The Experiment
The Experiment
Notes Before You Start:
Notes Before You Start:
Launches should be done in an open space or outside
Aim the launches away from people or animals
Clean up any mess made from this activity
Be careful when handling the hot glue gun and get help from an adult
BE SAFE!
What You'll Need:
What You'll Need:
7 craft sticks (jumbo works best but regular sticks are fine)
4 rubber bands
A small lid (a bottle cap lid)
Hot glue gun
Small candy (conversation hearts, skittles, m&ms, etc.)
Now let’s get started with the experiment!
Experiment Steps:
Experiment Steps:
Count 5 popsicle sticks and stack them on top of each other. Tightly bound both ends of the stack of popsicle sticks with one rubber band on each side.
Take the 2 other popsicle sticks and stack them on top of each other. Take one rubber band and tightly wrap it around one end on the stack.
Take the stack of 2 sticks and separate the unwrapped part of the stack without undoing the wrapped end. Place the stack of 5 popsicle sticks in between and push it as close to the closed edge as it can go.
Take the final rubber band and criss-cross it around both stacks to secure the two parts in place.
Image of steps 1 - 4
Completed Catapult
5. *Adult assistance required* Take the glue gun and squeeze a pea-sized amount on the top end of the popsicle stick and place the bottle cap lid on the glue and let it dry. This is the launchpad.
6. Now, be safe, but HAVE FUN! Make sure you are in an open area, take a piece of the candy, and put it in the bottle cap (launchpad). Make sure one hand is on the base (5 stick stack) to keep the catapult stable. Take your other hand, push down on the cap, release, and watch the candy launch!
Explanation
Explanation
This mini catapult works similarly, if not the same, as regular catapults. This popsicle stick catapult is a simple machine (a mechanical device used to change the direction or magnitude of a force). When you press the arm/launchpad (bottle cap) down, tension builds, and energy is stored (elastic energy). When you release the launchpad, the elastic energy converts to kinetic energy. When the arm is stopped, the object on the launchpad (candy) moves at the same speed as the arm because of Newton’s first law (an object in motion, stays in motion unless acted on by a force).
Depending on how far you push the launchpad down, the item will launch to different places.
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