Re: [Phys-L] 9th grade energy resource projects

[Bernard Cleyet <bernard@cleyet.org>]

On 2014, Dec 09, , at 09:48, Bill Nettles <bnettles@uu.edu> wrote:

> The corollary to this would be that the more lights you connect in parallel, the harder you have to pedal to keep them bright.  I don't know if there are any simple torque sensors available so making measurements of this effect would be a good challenge.


Reminds me of the question posed on an horological list:  The energy “contained” in a wound clock’s main spring.  

I attached a rod to the winding key, and used a spring gauge to measure the force.   From the lever arm the number of turns, etc. AND a crude integration from measuring the increased torque every several turns found the E.  Much greater than I expected, and explains why horologists warn when releasing the pawl of a wound spring to “take great care”!  


So a lever arm attached to the bicycle’s crank or just simply put a weight on the pedal.

bc