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Re: [Phys-l] Energy Transfer with hammers



You left out material strength, which is essential in designing objects which hit other objects.

From Mechanics of Materials, Beer & Johnston
Ultimate
Material Yng mod (GPa) density (kg/m^3) strength (MPa) Yield (MPa)
Stainless 302 cold rolled 190 7920 860 520
Titanium 114 4460 900 825
Aluminum 6061 69 2710 290 255
Aluminum 2014 72 2800 480 410

Aluminum would either deform permanently or break long before titanium would. Titanium provides an outstanding strength to density ratio so that a large head speed can be generated (KE) more easily (lower moment of inertia), there is a balance of "flex" in the face (of hammer or golf club) between steel (stiff) and aluminum( mushy), but you don't permanently deform it....

Bill Nettles
Union University
Moses Fayngold <moshfarlan@yahoo.com> 7/14/2009 7:28 am >>>
I do not see a straightforward way from the relevant characteristics of Titanium to the claims made.
In terms of the Young modulus and specific gravity, the basic characteristics determining other properties like speed of sound etc., we have from Phys. Handbook:
Young modulus (GPa) Specific gravity
Stainless steel 200 7.9
Titanium 109 4.5
Aluminum 70 2.7

In both these characteristics, Titanium is between steel and Aluminum. If Titanium's mechanical properties are, indeed, responsible for its performance allegedly superior to that of a steel hammer, then the Aluminum hammer could be expected to do even a better job.
Also, I did not see in the referenced sources any reproducible experimental tests; instead, we have just statements based mostly on personal experience of some workers, most of whom remain unknown except for their email ID.
At this level, the whole thing seems unsubstantiated.

Moses Fayngold,
NJIT




________________________________
Bob LaMontagne, <RLAMONT@providence.edu>, wrote:

To: Forum for Physics Educators <phys-l@carnot.physics.buffalo.edu>
Sent: Monday, July 13, 2009 7:01:50 PM
Subject: Re: [Phys-l] Energy Transfer with hammers

Sounds a lot like the claims made in ads for selling golf clubs in various magazines!

Bob at PC

________________________________________
From: phys-l-bounces@carnot.physics.buffalo.edu [phys-l-bounces@carnot.physics.buffalo.edu] On Behalf Of Jack Uretsky [jlu@hep.anl.gov]
Sent: Monday, July 13, 2009 6:49 PM
To: Forum for Physics Educators
Subject: Re: [Phys-l] Energy Transfer with hammers

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?
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--
"Trust me. I have a lot of experience at this."
General Custer's unremembered message to his men,
just before leading them into the Little Big Horn Valley



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