17 Joules of Energy From a Mouse Trap

Question

Do you think it would be possible to get 17 joules out of a standard size mouse trap. By my math, it is a torsion coefficient of 3.45 or so out of the spring.

Answer 1

I haven't used a mousetrap for several decades, but as I recall the moving arm is about 5cm long, so the tip moves 0.05$\pi$ or about 0.16m. To get 17J of work the force at the tip of the arm would need to be 100N. I'm fairly sure the force isn't anything like that great. I remember being able to pull the arm back with one finger. I would guess the force is nearer 10N, so you'd only get around 2J out.

Answer 2

Yes, if you burn it. Neglecting the metal, a $25\ g$ wooden mousetrap at $15\ MJ/kg$ should yield about $375\ kJ$.

Answer 3

Good guesstimating John Rennie. This fellow did some measurements (on a rat trap) and got slightly over 3 Joules:

http://www.instructables.com/id/Mouse-Trap-Speed/step4/Analysis-using-Basic-Physics/

Answer 4

$$U=\frac{1}{2}k\theta^2$$. A standard mouse trap is usually set at $\approx 180^o=\pi\space$ radians. $$\therefore U=0.5*3.45*\pi^2\approx17.025\space J$$ Of course, the torsion law is only an approximation, and it may decrease after use of the moustrap, so the energy obtained would be slightly less.

EDIT: I seem to have misunderstood your question. I don't have any idea what the torsion constant of a spring should be, but 17 joules is pretty small.