Mouse Trap Car Calculation

[jk_zhengli]

i have to make a mouse trap car in physics class and calculate a several things afterward. Anyone can help me to calculate the engergy stored n mouse trap based on measurements, ideal machanical advantages and percent efficiency. The mouse trap produces 5N at a 90 degree angle and 11N at a 180 degree angle.

[berkeman]

To calculate the energy stored in the spring, you would integrate the force multiplied by the distance as you push the bar from zero to 180 degrees. You can probably use a linear extrapolation of the force by angle, based on the two numbers you are given.

One simple way to make a mousetrap car is to put a lead weight on the bar (and wheels on the wood piece, obviously). Springing the trap will fling the lead weight backwards, and propel the car forwards. What other ways can you think of to convert the stored spring energy into motion? How can you compare the efficiencies of the different conversion mechanisms?