Catapult!

[JohnnyEgo]

Can you show some pictures of how you adjust the angle?

Pretty simple, really. The pivot arm is also the rotational axis. I had him measure and draw out all the angles between the side plate and the base, and then drill the holes so that two pins would fix it at the desired angle. He did pretty good for most of them, but was a little off on one of the 90 degree holes, which is why the upper front holes have one extra. I told him it was a feature; extra pin holder.











I had thought the hardest part of this whole thing would be explaining force vectors and free body diagrams to a 10 year old with zero knowledge of algebra or trigonometry. Turns out the hardest part by far was getting him to sit in a chair long enough to type up what he learned and fix the spelling and grammar errors.