What are similarities between a catapult and joint?

Answer 1

the similarities between a catapult and a joint are that both spring backwards and forwards in a certain motion and path. for example, the elbow springs forwrds and backwards whilst doing exercise, and the great catapult fires its long arm forwards with the contents of the top flung forwards, the arm then taken back .

The similarites are that they both work under the physics principles of levers. The elbow, for instance, is a Class I lever when you extend it and works the same way as a counterweight trebuchet. Another example based on levers is the knee. When you extend it, it works on the same principle as a traction trebuchet which is a Class III lever.