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Pumpkin launcher

Question: We are in 11th grade and we were assigned a project that has to do with making a PUMPKIN LAUNCHER. I am totally clueless and have been on countless sites!! I was wondering if you could maybe point me in the right direction.
The pumpkin must be at least 2 kg and we are not allowed to use motors or fossil fuels. Any advice would be a huge help.

Answer:

Two possibilities:
(a) Use a giant piece of elastic in various forms
(b) Use a lever principle

Using the elastic

Fix the two ends of the elastic to two trees and then simply pull it back and down. Be careful not to let the elastic launch you as well as the pumpkin.

Using the lever

Put the pumpkin on the end of a lever far from the pivot. Then either push the other end down using your hands or drop a rock onto it. This will project the pumpkin from the other end. Of course if the end without the pumpkin is fairly close to the ground you could just jump on it instead of dropping the rock.

Romans and siege engines!

A slightly different idea was used by the Romans in their siege engines. Basically the machine, called a ballista, used a long lever with a rope fixed to one end the end furthest from the pivot. The other end of the lever was tied securely to the frame of the launcher. The rope went round an axle which had a ratchet to stop it turning one way. The projectile was put on the end of the lever above the rope.

The axle was then turned so tightening the rope and bending the lever downwards. (Rather like a giant bow).
When the lever was sufficiently bent the ratchet on the axle was released and the lever sprang up so launching the projectile in your case a pumpkin. They were extremely effective!
 

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