On Sat, 22 Feb 2014 00:52:14 +0000 (UTC),
(Larry W) wrote:

In article ,
wrote:
On Thu, 20 Feb 2014 14:40:05 -0600, Leon lcb11211@swbelldotnet
wrote:

On 2/20/2014 2:23 PM, wrote:
*Should be "of equal mass and close mass distribution"

And please don't swap the terms. Recoil? Leon likes the term bounce back

Bounce back = Energy that is not entirely absorbed by the strike and
which is deflected.

Right. Energy that isn't absorbed is useless, however that which isn't
moving the struck object is just being absorbed uselessly as heat
anyway. I don't see that the lack of "bounce" necessarily makes the
hammer more "efficient". It just means it's absorbing energy, rather
than the user's arm.

Recoil is a good term. Not all of the energy spent inside a bullet is
pushing the bullet down the barrel, much is absorbed by the person
shooting the gun.

Newton's third law kinda makes this a given.

It also depends on your definition of what an "efficient" hammer blow is
and what its purpose is. If I remember my physics right, there actually
is a _greater_ transfer of kinetic energy to the strcuk object when the
striking object rebounds. Conservation of momementum demands it. On the
other hand, that's based on "inelastic" objects and and when there's
deformation then things are calculated differently.

You just contradicted yourself. There is *not* a greater transfer of
energy if the hammer rebounds. The energy required for the rebound is
not imparted to the object, which is sorta the purpose of striking it
in the first place. There is no such thing as conservation of
momentum, in this case. There is *always* conservation of (matter
and) energy.

Maybe the deformation is what you're after, rather than kinetic energy
transfer.

Deformation is kinetic energy transfer. You're converting the kinetic
energy into heat (still kinetic energy with perhaps some potential
energy in a chemical/physical state change).

I've been away from the math of physics for too long to
figure out or remember how this translates for instance into driving a
tenon into a mortise or other common tasks. I'm sure one of our
engineer participants will address this soon enough.

It all turns into heat. ;-) You're trading the kinetic energy from
the hammer into heat from friction (heat/kinetic energy) of the
mortise into it's tenon.