Re: [Phys-l] Energy Transfer with hammers

[Brian Whatcott <betwys1@sbcglobal.net>]

Jack Uretsky wrote:
> What makes you think that the statements are correct?
>  			Regards,
>  				Jack
>
>
> On Mon, 13 Jul 2009, chuck britton wrote:
>   
> > http://www.finehomebuilding.com//item/8391/titanium-hammers-up-for-
> > grabs-want-one
> > has an interesting 'claim' about energy transfer.
> >
> > "My reason for going with titanium: energy. A titanium hammer
> > transfers 97% of your energy from swinging the hammer to the nail
> > head, while a steel hammer transfers only 70% of your energy to the
> > nail. Titanium drives a nail more efficiently and there?s less recoil
> > energy to travel back into your arm."
> >
> > This seems to BEG for some simple 'Mechanics' analysis.
> > Maybe 'Impedance matching'?	admittedly - NOT a topic usually covered
> > in intro mechanics but maybe it SHOULD be?
Simple? Here's a start, with an off the top speculation:
        if the titanium head were lighter -  as it ought to be,
and if it could be swung faster as it presumably could be, but if the 
speed of
sound in this less dense material is appreciably slower than the speed of
sound in steel, then  it might be possible to provide a somewhat greater
kinetic energy which could be delivered over a somewhat longer period to
the nail head before the compression wave in the hammer head
- whose material has a comparatively low elastic (Young's) Modulus -
motivated the recoil which would end the impulse....
[unresearched and unsupported...]

Brian w