The optimal length for the string on a mousetrap car can be determined by taking into account the size and weight of the car, as well as the distance you want it to travel. Generally, a longer string will allow for more distance, but it should not be too long as it can cause the car to lose tension and not travel as far.
The best type of string for a mousetrap car is one that is strong and lightweight. Fishing line or nylon string are popular options, as they can withstand tension and are easy to attach to the car. Avoid using thick or heavy strings, as they can add unnecessary weight to the car and affect its speed and distance.
The string should be attached to the back of the car. This allows for the car to move in a forward direction when the string is pulled taut. Attaching the string to the front of the car may cause it to move backwards or not move at all.
To ensure that the string stays attached to the car, it is important to secure it tightly with a knot or tape. You can also wrap the string around the axle or other parts of the car to keep it in place. Additionally, make sure that the string is not tangled or twisted, as this can cause it to come loose during the run.
Some additional tips for optimal string attachment include using a lightweight and sturdy attachment point on the car, such as a small hook or eyelet. It is also important to make sure that the string is not too loose or too tight, as this can affect the car's performance. Experiment with different lengths and types of string to find the best fit for your specific mousetrap car design.