pining,twin plugging,etc...

[Joe Boucher]

Thsi is one wild discussion.

At 06:38 PM 3/10/98 -0700, you wrote:
>
>
>Lino Verna wrote:
>
>> When you push on a wall with 200lb's of force it
>> >> pushes back with the same amount and yet it did not
>> >> move,,,hmmmmmm,,,,but it is stored energy
>>
>> >
>> >If you push on the wall and it pushes back, but nothing moves, you've
>> >created heat!  Energy dissipates into the air.
>>
>> >Wouldn't stored load be called inertia?  I seem to remember doing some
>> >inertia equations in a physics class.  Can't remember the equations but I
>> >sure remember doing them.

Inertia is resitance to change in movement and is a property of mass.  More
mass, more resistance.  Stored energy is potential energy, for example, a
compressed spring (or wall) or water about to flow down a tube and through
a turbine to make electricity.

>> Actually the wall does move, and that is how it stores the energy.
>> Push on anything and it will move.
>>
>> Tell you what, put on that cone shaped hat like the rest of us wear and
>> jump.
>> I guarantee that the earth will move the other way as a reaction to your
>> jump.
>> That is, only if you're wearing that hat though...
>>
>> lino
>
>  Ahhh!  But the measure of anything depends on a reference point.  With
Earth
>as a reference point, only I and my cone shaped hat will move.  When I land,
>the Earth is not moving, and much too quickly I am not either.  But I sure
>have expended my energy and likely cannot find any of it stored up in the
>place where I hit.
>
>Believe me about this.  I have a subscription to the cone shaped hat of the
>month club.
>
>Ok, I'll probably get flamed for this, but there are circumstances where
>pushing can't cause movement.  There is simply not enough force in the push.
>Maybe where I'm getting confused is my idea about "stored" energy.  It seems
>that if energy were being stored in the wall, it would be accessible.  Like a
>flywheel spinning on a shaft has stored energy.

In practical terms you're correct.  But in reality if you push on something
there is movement.  You might have to get down to the point of watching the
atoms at the area of the push to see the movement, but it's there.

>But how can you measure the energy "stored" in the wall?  Some of you ME
types
>can surely help me here.  

Potential energy stored in a spring is 1/2 times the spring coefficient
times the square of the compression distance.  Tell me the spring
coefficient of the wall and we'll figure it out.  Can we convert the stored
energy into real work.  No.

>It seems that there is certainly a definition of
>pushing without movement.  It's called Force.
>And pushing with movement is Work.  ('course pushing without movement can
be a
>lot of work, too).  So the energy must go somewhere.  In many cases it's
heat.
>But what about gravity and the telephone supported by my computer table......
>If I balance this glass of water like so... ah, but, um,,,
>
>Uh-oh.  My wheels are spinning again.
>
>Time to go re-arrange the hat collection.
>
>Shannen


I sure miss the dormitory bullshit sessions.
Joe Boucher
'70 RS/SS Camaro  '81 TBI Suburban