1. I believe a spinnig wheel's inertia increases and needs MORE force
to push it?

2. I believe it's relavistic mass doesn't increase (since very low
velocity using the gamma equation)?

3. In that case a spinning wheel would NOT weigh more?

----------------------------------------------

Excluding friction, the pushing Force on a static object is Fpush = Mg
(M is invariant correct?)


4. Since for a Spinning wheel: Fpush = Mg is insufficient (we need to
add moment of inertia somewhere)

*********then shouldn't Fpush = Mg also be INSUFFICIENT for a static
object *SINCE* it also has electrons & protons spinning around the
nucleus, no??************

if #4 is corect and Fpush = Mg is correct for static objcets, since
Fpush and g don't change therefore M must be the one that is inaccurate
and not truly the invariant mass of the object, no??


Something doesn't make sense above but I can't pin point it?

wrote in message
oups.com...

1. I believe a spinnig wheel's inertia increases and needs MORE force
to push it?

If by that you mean you need a greater force to cause the same increase in
rotational velocity - yes. But at ordinary velocities the effect is
negligible.


2. I believe it's relavistic mass doesn't increase (since very low
velocity using the gamma equation)?


Its relativistic mass increases. The thing is these days relativistic mass
is an archaic concept not used much.


3. In that case a spinning wheel would NOT weigh more?


Yes it would.


----------------------------------------------

Excluding friction, the pushing Force on a static object is Fpush = Mg
(M is invariant correct?)


In this case M is not invariant because what you are considering consists of
a spinning wheel - this is one case where the concept on relativistic mass
is useful. Its rest mass remains the same however. The 'mass' increases
hence the force increases.



4. Since for a Spinning wheel: Fpush = Mg is insufficient (we need to
add moment of inertia somewhere)


The equation looks ok.


*********then shouldn't Fpush = Mg also be INSUFFICIENT for a static
object *SINCE* it also has electrons & protons spinning around the
nucleus, no??************

Electrons are quantum objects so do not spin or move around the nucleus -
velocity is not a quantum observable. Electron spin is a quantum concept
not having an everyday analogy to the usual concept of spin as something
rotating on its axis.


if #4 is corect and Fpush = Mg is correct for static objcets, since
Fpush and g don't change therefore M must be the one that is inaccurate
and not truly the invariant mass of the object, no??

Fpush does change due to the increase in relatvistic mass.

Thanks
Bill




Something doesn't make sense above but I can't pin point it?

wrote:
1. I believe a spinnig wheel's inertia increases and needs MORE force
to push it?

It does if the push alters the axis of rotation
wrt the universe's mass.
http://hyperphysics.phy-astr.gsu.edu.../gyr.html#gyr3


2. I believe it's relavistic mass doesn't increase (since very low
velocity using the gamma equation)?

Try telling that to a lawyer as he compares the depression
a bird shot makes, held in the palm of his hand, with the
depression made by bird shot ejected from a lunatic's
gaming piece.

If you really beleive it, you can save some money on
the optional scatter shield if you ever replace your
automobile motor with a flywheel. )


3. In that case a spinning wheel would NOT weigh more?

One way or another, it's mass/energy equivalent is going
to be expressed... Heating bearings, stirring up and heating
gas or heating a scatter shield.

Drop a 1 kg weight into a bucket of water and drop
a 1 kg spinning gyro into a similar bucket of water.

The spinning gyro will raise the water temperature
more than the weight.

Sue...


----------------------------------------------

Excluding friction, the pushing Force on a static object is Fpush = Mg
(M is invariant correct?)


4. Since for a Spinning wheel: Fpush = Mg is insufficient (we need to
add moment of inertia somewhere)

*********then shouldn't Fpush = Mg also be INSUFFICIENT for a static
object *SINCE* it also has electrons & protons spinning around the
nucleus, no??************

if #4 is corect and Fpush = Mg is correct for static objcets, since
Fpush and g don't change therefore M must be the one that is inaccurate
and not truly the invariant mass of the object, no??


Something doesn't make sense above but I can't pin point it?

"Sue..." wrote in message
ups.com...
wrote:
1. I believe a spinnig wheel's inertia increases and needs MORE force
to push it?

Very handy, spinnig wheels are.
Rumpelstiltskin made gold out of straw with one of those.
http://www.geocities.com/Heartland/E...67/rumpel.html

However, Gus may asking about
http://www.zephyrus.co.uk/horsepoweranswer.html
(or he may be just spiggin' his wheels).

Androcles

wrote:
1. I believe a spinnig wheel's inertia increases and needs MORE force
to push it?

You need to be a bit more precise, but for a push along its rotation
axis, yes. This is no different from the observation that heating an
object also increases its inertia -- for an object of definite size with
a rigid boundary on which you push along an axis containing its center
of mass, its inertia is proportional to its total internal energy.

By "inertia" I mean the "m" in the equation of motion
m dU/d\tau = F (valid for constant m); U is the object's
4-velocity, \tau is its proper time, and F is the applied
4-force.

This is in the context of SR.


2. I believe it's relavistic mass doesn't increase (since very low
velocity using the gamma equation)?

You must use a consistent approximation. If its "inertia" increases, so
does its "relativistic mass".


4. Since for a Spinning wheel: Fpush = Mg is insufficient (we need to
add moment of inertia somewhere)

That's why I specified "along its rotation axis". For any other axis
this is _much_ more complicated.


Tom Roberts