After modifying our mousetrap car today in class, we found that the complications were the eye hooks, the string, and the cardboard body. The eye hooks were too loose around the axles, and were not strongly attached to the body, so when we tried to run a trial the eye hook turned and the weak body bent in such a way that the string could not unwind and the axle could not turn. The string became tangled around the axle and around the mousetrap itself, making it so that the potential energy of the mousetrap spring could not be transferred into making the car accelerate. The cardboard body wasn't sturdy enough to support the eye hooks and the mousetrap, and bent when the wheels and axles turned.
When our modifications failed, we decided to construct a whole new mousetrap car, because the body and its connection to the axles all had to be replaced.
Our new prototype looks like this:
The body is a tissue box, and the wooden dowels (the axles) are going through the body, which proved to be a sturdier connection than with the eye hooks. The CD wheels are attached by corks to the axels. We remade the wheels to be wrapped in duct tape to provide traction. The body is held in place by tape wrapped round the dowel on the outside of the body. The mousetrap "engine" is hot-glued to the base of the tissue box, and a shorter piece of string is tied to the snapper arm and the back axle.
We only had time to run one trial with our new prototype, and it managed to accelerate at a decent velocity. This is a good start, but we still need to keep improving this model!
