Re: [Phys-L] Demonstrating energy and levers

[Bernard Cleyet <bernardcleyet@redshift.com>]

On 2013, Nov 19, , at 17:25, Doug Peltz <dougpeltz@gmail.com> wrote:

> Does anyone have a good idea for how to show the energy input on one side
> of the lever and the energy output on the other side?  I can show the force
> input & output by hooking up newton meters, but how can I do this for
> energy?


Do your students “understand” potential E, as in Mg•h and 0.5 kX^2 (Hookian spring)**.  If so, use each at the ends of a lever.  Move the fulcrum about and (still) get equality.  If the fulcrum is not centered first balance the lever (with masses).  Then add mass to stretch the spring.  Obviously, I pray, with a multiplier less mass required to stretch a given distance, and the mass moves further.



** as lin. doesn’t require calc, no?

bc prays he’s not mixed up and doesn’t think it’s necessarily a good method.  

p.s. I suspect knwing K unnecessary , but easily found with the fulcrum centered. Further thought, yes.  And only requires four length measurements, and known masses, no?