Among the various types of catapults, the trebuchet was the most accurate and among the most efficient in terms of transferring the stored energy to the projectile. In addition, it allowed greater consistency in the throws due to the fact that the same amount of energy could be delivered every time, by way of a raised counterweight. A trebuchet works by using the energy of a falling and hinged counterweight to launch a projectile the payload , using mechanical advantage to achieve a high launch speed.
For maximum launch speed the counterweight must be much heavier than the payload, since this means that it will "fall" quickly.
The physics behind a trebuchet is fairly complex. A detailed explanation of it is given on the page on Trebuchet Physics. In some designs a guide chute is used to guide the sling along and support the payload until the speed is great enough to hold it in the pouch alone. The beginning of the launch is illustrated in the figure below.
As you can see, the counterweight pivots around a much shorter distance than the payload end. The advantage of this is that the payload end of the beam reaches a much higher linear velocity than the counterweight end of the beam. This is the principle of mechanical advantage, and is what allows the payload to reach a high launch velocity.
However, because the counterweight pivots around a much shorter distance, its weight must be much greater than the weight of the payload, to get a high launch velocity. However, increasing the mass of the counterweight beyond a certain point will not help, since the limiting speed of the falling counterweight is free-fall speed. At this point the ring which is connected to the sling and loops around the finger for support slips off and the payload is launched.
The figure below illustrates the trebuchet at the release point. As the beam rotates clockwise due to the falling counterweight , the payload experiences centripetal acceleration which causes it to move outwards since it is unrestrained. This results in a large increase in linear velocity of the payload which far exceeds that of the end of the beam to which the sling is attached.
This is the heart of the physics behind a trebuchet and is the reason why a trebuchet has such great launching power. For a more in-depth explanation on how a trebuchet works see Trebuchet Physics. In this page the basic equations describing the physics of a trebuchet will be introduced. To assist you in building a trebuchet you can use this simulator to help you come up with the design that throws the payload the farthest. This is very useful for helping you come up with the winning design in a trebuchet competition!
In the next section we will look at the mangonel. Author: ChrisO The above picture of the mangonel is what people are most familiar with when they think of catapults. We use cookies and other tracking technologies to improve your browsing experience on our site, show personalized content and targeted ads, analyze site traffic, and understand where our audiences come from. To learn more or opt-out, read our Cookie Policy. In this video for kids, we build our own marshmallow-launching machine.
Welcome to our first-ever week of Vox Video programming for kids! Watch the above video to see how we did it. Leonardo da Vinci was a famous artist and inventor, and his sketchbooks include a couple of catapult drawings that you can use to make a catapult model. We did just that, and it was a lot of fun. Catapults have a long history, going back to the ancient world and appearing all across it, from China to Rome. They were used throughout history to bombard castle walls and enemies with projectiles, and they were adapted in the Middle Ages into agents of biological warfare.
There are different types, like a mangonel, a trebuchet, and a ballista, each of which has unique advantages. Build a Cardboard Catapult. So, this week, your mission- -should you choose to accept it—is to build a cardboard catapult , mostly from things you have on hand at home: wood paint stir stick available free from any store where you can buy paint… they type you use to paint the walls of your house. Instructions for making a cardboard catapult. Catapult Test Sample Graph Paper.
Create a game with your catapult. How can you make it more fun? More challenging? What can you do to tune your catapult to hit your target? The Geometry of catapults. Test a cardboard catapult - part 1 - Catapult egg test.. Materials needed : A cardboard catapult made last week A digital scale to weigh your projectiles A tape measure … so you can measure how far your projectiles fly A variety of balls to test your catapult… such as a cotton ball, ping pong ball, whiffle ball, golf ball, small bouncy ball… even small nuts or pine cones.
You can use silly putty to make and test different sized balls. A sheet of paper to record the distances your projectiles go. A piece of graph paper template provided to plot your results. This even works on concrete like a driveway! I used position 3. STEP 2 — Select your projectiles and weigh them, and record that on your data sheet. STEP 4 — Check the distance each projectile travels—look for the white mark—and record that on your data sheet next to its weight.
SO… Advanced question…. What can we do to alter our hang time? Is there a way to jump the curve and get even more distance? Any ideas how to do that? Can you think of other games you can play with your catapult? SHARE a picture or video of your catapult by posting in this thread! Data Sheet. Graph Paper. Good luck! Only your first name will be posted on my website with your experiment photo and video.
Accepted file types: jpg, png, pdf, Max. Upload any photo you'd like of your experiment.
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