Physics experiments bring catapults to the attention of many students. There are various ways to build one, this is quick and easy. The most powerful catapults use a long arm, with the fulcrum in the center, using springs or the force of torsion to propel the projectiles.
Steps
Method 1 of 3: Part 1: Building the Structure
Step 1. Prepare the left side
On the table, place a 5x10x90cm board with the wide side down. Next, place a 5x10x37.5cm plank so that its right edge is 37.5cm from the head of the 90cm piece.
Step 2. Join the left side to the left base
Drill two holes in the ends of the 37.5cm piece, which also go through the 90cm piece. Push pegs sprinkled with glue into the holes you just made to hold the pieces together. To do this you will need a hammer.
Step 3. Repeat
The right side has exactly the same construction.
Step 4. Nail the support boards
Cut a 37.5x46 board, a little over one centimeter thick, along the diagonal. With nails, secure each of the halves to either side of the catapult. This will provide it with great structural strength.
Step 5. Join the two sides
Using screws and two other 5x10x37.5 boards, join the two sides to complete the base: one must join the two front ends of the sides, the other the rear ones. Run the screws through the sides of the catapult, and into the heads of the aforementioned boards.
Method 2 of 3: Part 2: Making the Arm
Step 1. Nail or screw a support board between the two sides, keeping the top face of the board level with the heads of the vertical boards
Step 2. Prepare the arm
Take a 5x10x75cm plank and measure 6.25cm from one end. Drill a 12mm hole centered there through the wide side of the board.
Step 3. Secure a plastic cup or similar container to the side of the arm opposite the one you just drilled
Step 4. Drill a 25mm hole in both sides of the base, from the side with the triangle
This hole should be centered 15cm from the head of the 90cm piece, and 6.25cm from the bottom edge.
Step 5. From a broomstick, make two handles
You will need them to twist the ropes and tension your arm.
Method 3 of 3: Part 3: Join the Arm
Step 1. It's time to tie the pieces together
Knot the rope around the handle, through the hole in the left side of the base, through the catapult arm, out of the hole in the right side of the base, and through the second handle. It will take several windings, and about 6m of rope.
Step 2. Anchor the pieces together
Start by securing the rope to the first handle, in the center of the handle. Go through all the pieces, wrap it around the other handle, then roll it back. Repeat 3 times.
Step 3. Lace up the sides
Now, pass the rope around one side of the handle through the side hole, skipping the arm, pass the opposite side, through the hole, around the handle, and back.
Step 4. Reverse and repeat
Reverse, so that the arm has passed to the opposite side as the first time and repeat for at least 6 passes. The rope should always wrap around the handles in the same way, but the reverse of how the arm is wrapped.
Step 5. Wrap around your arm
When you reach the end of the rope, wrap it around the whole bundle that enters one side of the arm and then the other side to switch to the other bundle of cables.
Step 6. Finish the catapult
Knot it all up and you're done! Twist the handles to tension the ropes, and thus the arm of the catapult. Have fun throwing objects and calculating trajectories!
Advice
- Makes the bullet release angle 45 ° if you intend to hit a target at the same level as you, lower if the target is lower down. If you are able to do the calculations necessary to use a catapult with precision, you will make a great impression!
- In the construction of your catapult, use a frame made of triangular elements. It is a naturally stable geometric figure, the three sides of the triangle cannot move unless they come undone, while a square risks collapsing into a rhombus.
Warnings
- You absolutely must keep out of the plane on which the catapult arm rotates, otherwise you risk finding it in your face.
- Once you have used the catapult, do not leave it outside. Children may want to play and hurt themselves!
