Physics at Home: Creating a Paper Trebuchet
"Hey, can you pass me a paperclip?" "Why yes, I'll send one with my paper trebuchet."What you Need
- Card stock
- 16 pennies
- Scotch Tape
- trebuchet template (downloadable in different formats from http://www.thingiverse.com/thing:16735)
- Download the appropriate template for you.
- Put the cardstock in your printer and print the downloaded template.
- Using a scissors cut out the image from the template following the solid lines (Do NOT cut the dotted lines!)
- Fold on the dotted lines.
- Latch the two notched pieces together.
- Make two stacks of pennies that are 8 pennies high each.
- Wrap the tape around the outside of the pennies to form two separate stacks.
- Place each stack of pennies in the two holes in the trebuchet you made.
- Bend a paper clip as shown.
- Raise the penny side of the trebuchet in the air by rocking the tooth side of the trebuchet toward the ground.
- Place the paper clip in the tooth of the trebuchet.
- Release the trebuchet.
- How far did your paper clip travel?
What's Going On?
This trebuchet isn't exactly like one you'd find aimed at a medieval castle, but it operates using the same principles. The side of the trebuchet with the pennies weighs more than the end with the paperclip, so when released, gravity pulls the penny end of the trebuchet quickly toward the ground. When the penny side drops, the other end pivots toward the sky, bringing the paperclip with it. As soon as the pennies touch the ground, the paperclip end of the trebuchet stops moving forward, flinging the paperclip from the trebuchet off in a straight line. The paperclip continues moving forward and falling down under the force of gravity, until it hits the ground. Essentially there are two planes of movement in which the paperclip moves, the vertical (up and down) plane and the horizontal (across) plane. If gravity and friction didn't act on the paperclip, it would travel in a straight line forever. Gravity is the force that sends the paperclip flying through the air and brings it back to the ground.
- Try flinging different sized paper clips. Do you notice a difference?
- Try setting up a target. How many times in a row can you hit your target?
- Try measuring the distance your paperclip travels. Under what conditions does your paperclip travel the furthest?