Play Catapult

Students will build a catapult to learn about motion and the forces acting upon the projectile. Catapults were used in history to launch a projectile that smashed buildings and walls during a siege. These weapons of war will now teach students about the forces involved in moving a projectile or acting upon the projectile to put it in motion and the energy required to do so.

Instructions

A Popsicle Stick Catapult

1 Glue together one whole Popsicle stick to one half Popsicle stick to form an L. Repeat the process to make another L. Glue the two Ls together to form a rectangle.
2 Make two more Ls from Step 1's instructions and glue them together to form another rectangle. Lay one rectangle on top of the other and glue them together to form the base of the catapult.
3 Mark the middle of the rectangle on both sides with a pen.
4 Glue two half sticks flat side down to your pen marks. These half sticks form uprights that are perpendicular to the foundation. The two uprights should be directly across from each other.
5 Glue a half stick to the foundation near the corner flat side down, with the other end gluing to the upright. This forms a triangle and act as a brace. Repeat this with the other side so the braces are across from each other.
6 Glue another half piece on the other side of your triangular braces. This will glue to each upright crossing the upright and forming a crosspiece. The piece is flat side down.
7 Fold your 1 1/2-inch square piece of paper in half. Roll the half together to form a cone. Cut the top of the cone in half.
8 Smash the bottom of the cone onto a whole Popsicle stick and glue it to the stick at the end. This is the throwing arm. The cup you just made is where the projectile rests.
9 Fold the piece of string in half, placing the ends in your mouth or have a friend hold onto it. Twist the string 10 to 20 times.
10 Fold the string in half again and secure the ends. Twist again 10 to 20 times.
11 Fold the string in half again and repeat the twisting process. You now have a strong twisted rope.
12 Thread the rope between the two full sticks under the cross pieces. Tie in place around the top stick with a square knot or double overhand knot. Move the knot to the side. The rope will go across the foundation to the other side, loop over the top part of the foundation and rest under the cross bar.
13 Use the last half piece of Popsicle stick as a twister. Stick the flat end between the ropes. Twist backwards away from the uprights the desired amount of times.
14 When the twister is as tight as desired, glue the throwing arm to the twister. Glue the non cup side to the twister and tightly hold while the glue sets. The cup should be upright and facing the uprights when completed. If done correctly, the arm should smack against the upright when done.
15 Hold the arm down. Put a projectile in the cup and release. Use the wadded up paper for a projectile.