Re: [Phys-l] pseudo-force

[Rick Tarara <rtarara@saintmarys.edu>]

But if you really analyze what you are feeling, I think it will never be 
directly the downward force of the earth on you.  For example, your 
outstretched arm:  What you feel is the muscular force that is holding your 
arm up. Same with your legs.  We are so used to INTERPRETING these upwards 
forces (floor, chair, bed, muscles) as the effect of our weight (downwards) 
that when in the forward accelerating airplane or the rotating 'rotor' ride, 
we again interpret the direction of the force that is actually there to be 
in the reverse direction.  I make this whole topic a major component in my 
gen-ed class.

Rick


----- Original Message ----- 
From: "Michael Edmiston" <edmiston@bluffton.edu>


> I'm confused by those of you saying we do not feel centrifugal force or
> gravity.  It is true that when I sit on a chair that I feel the chair.
> But what about when I hold my arm straight out to the side, or more
> difficult (for me), what about when I lay on the ground and try to do
> leg lifts for very long.  Am I not feeling gravity when I do that?
> Something is pulling my legs down, and it isn't the floor because my
> legs aren't touching the floor nor are they tied to it.
>
> And if I am facing inward in a centrifuge with my back and arms and legs
> being pushed from behind by the wall of the centrifuge, what if I try to
> pull my arm away from the wall, or try to do leg lifts in that
> situation.  Am I not feeling a centrifugal force?  And if the centrifuge
> speeds up, don't my leg lifts get a lot more difficult?
>
> Every morning when I wake up, I feel the bed.  As I try to get out of
> bed I also feel gravity.  Lately I find the bed feels a lot nicer than
> gravity.
>
> Michael D. Edmiston, Ph.D.