Humans love to throw objects fast and far, but there is a limit to what we can do with our arms alone. One of those early creations was the catapult, a device that stores up energy as potential energy to be released all at once as kinetic energy that throws a projectile much further than a human could alone. To make our catapults, we will use something that engineers utilize every day: The Engineering Design Process.
This is a circular, six-step plan that helps us create the best possible solution to a problem. From NASA who knows a thing or two about engineering , we learn that the engineering design process is:. Broken toy? This can help you fix it. Argument with a friend? Try following these steps to figure out a solution — instead of building a machine you are using the steps to plan out the conversation you will have with them. While this is the list of materials we used for our catapult , your materials may vary.
Remember, we are going to use the engineering design process we mentioned above as a guide for making our catapult. Keep going through the cycle until you are satisfied with your design. There are numerous ways to make a catapult using materials found at home and we encourage you to try different ways.
To get you started, here is one possible method, followed by photos of other example builds. Materials can and should! Attach the throwing arm to the stack with elastic bands, wrapped in a crisscross pattern. The more secure the attachment, the more spring you will get from your catapult. Build the base of the catapult. Arrange the catapult so the stack of craft sticks is laying on the table, and the throwing arm is sticking up.
Add a small dab of hot glue to each end of the stack and glue a craft stick to each end. Add another dab of glue to the end of each support you just added, and use an additional craft stick to attach the two ends, creating a rectangular base. Reinforce the throwing arm. This step is optional, but will add additional stability and power to your craft stick catapult. Cut or break off a 2-inch piece of craft stick. Add a dab of hot glue to the middle of the support beam that is parallel to the fulcrum stack, and attach the piece of craft stick.
Thread an elastic band over the throwing arm, and pull the end under the base of the catapult and secure it to the craft stick stub you just created. Attach the bottle cap to the throwing arm. Add a small dab of hot glue to the end of the throwing arm, and press the bottle cap into the glue, holding it in place for a few seconds while the glue cools.
Fire away! This catapult should have a longer range and more accuracy than the basic craft stick catapult in Method 1. Method 3. This catapult design project is used to teach engineering skills to children.
It builds a slightly more complex torsion catapult than the previous methods, but requires just a few additional supplies and steps. Ping pong balls and grapes both work well with this catapult project. Build two uprights for the catapult. Create a second upright that is the mirror image of the first. Build a base to hold the uprights.
Place a dab of hot glue on each of the bottom legs of the first upright, and attach a craft stick connecting the two so that the vertical portion of the upright attaches to the end of the base. Repeat this process with the second upright. Then use hot glue to attach one additional craft stick to the front of each of the uprights. The base should now form a rectangle with one end open, and the two uprights sticking up parallel to one another.
Add the fulcrum to the catapult. Cut a 2" length of straw and slide the dowel through it. Use hot glue on to attach the dowel firmly to the wedge formed at top of the each upright. Build the throwing arm. First loop an elastic band around the craft stick that connects the two uprights. Finally, carefully attach the other end of the rubber band near the bottom of the large craft stick.
The throwing arm should now be able to rotate freely around the dowel on the straw, and the elastic band will put tension on the throwing arm as you pull it back. To create a strong bond with the throwing arm, use a pencil or other tool to press the elastic band firmly into the hot glue, and hold it for a few seconds until the glue cools. Do not use your fingers or you will burn yourself!
Add the finishing touches. Your catapult is nearly ready to go, but a few more steps will make it sturdier and easier to use! Attach the milk jug lid to the free end of the throwing arm with a dab of hot glue. Attach one additional craft stick horizontally to connect the slanted sides of the two uprights and provide additional stability.
Add additional craft sticks to the bottom of the catapult that out as needed to keep the machine stable while firing. Fire your catapult! Load a ping pong ball or grape into the milk jug lid. Pull back the throwing arm and let fly! For building the more advanced torsion catapult, can I use jumbo Popsicle sticks instead of regular? Yes No. Not Helpful 15 Helpful Yes, you can fire marshmallows with it, as long as they don't stick to the bottle cap. This activity brought to you in partnership with Science Buddies.
Already a subscriber? Sign in. Thanks for reading Scientific American. Create your free account or Sign in to continue. See Subscription Options. Discover World-Changing Science. Key concepts Physics Engineering Elastic potential energy Projectile motion Introduction Catapults were mighty handy for pirates in the golden age of piracy during the 17th century. Materials Eight craft sticks popsicle sticks Four or five sturdy rubber bands Glue Plastic bottle cap to hold a cotton ball Cotton ball If you do not have any available, you can make a small ball by crumbling some paper.
Small open area One square meter will do. It should be a sturdy, flat surface such as a table or floor. Preparation Note: The simple catapult described in this project is safe when used with a cotton ball. Shooting hard objects or using other homemade catapults can be dangerous. Make sure any objects you launch are soft and light so as not to harm anyone or cause any damage to objects around you. Take six craft sticks, stack them one on top of the other. Secure these sticks together by wrapping rubber bands around both ends of the stack.
You will anchor the launching stick to this stack, as described in the next step. To add the launching stick take one stick and attach it perpendicular to the stack you just made, around the middle, so you get a cross shape. You can do this with one or two rubber bands that are crossed in an X over the sticks. If you cross it this way, the sticks will stay nicely perpendicular.
Next, add the base by attaching a stick to one end of the launching stick with a rubber band. If it were not for the stack of sticks in between, the launching stick would fall flat on top of the base. Now the launching stick and the base form a V shape lying on its side with the stack of sticks in the middle. Put your catapult on its base, locate the end of the launching stick that sticks up and glue the bottle cap there so it forms a small cup to hold the missile.
Wait until the glue is dry. Procedure Put your catapult in an open area with a sturdy, flat surface such as a table or an open space on a hard floor. Clear about a meter of open space for the launched object the missile to fly and land. Place a cotton ball in the launching cup, push the cup down just a little bit and let go.
What happened to the ball? Did it fly?
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