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the perception we are talking about is called __EFFORT_______
and is roughly proportional to some physical quantity
namely __IMPULSE (not work) ________
because __the difficulty depends on how much you are asking your muscles to
contract, and how LONG they must keep up this effort _
this physical quantity depends on _FORCE__ and __TIME__
on the upstroke this evaluates to _m*g*t(up)
on the downstroke this evaluates to _m*g*t(down)
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If you do this in the same time, the "effort" is the same. Some comments:
* The force required of the *muscles* isn't really "mg". Since the muscles
are attached near the end of the lever arm, the force is actually much
greater, however, this correction is the same in both directions, so it
doesn't really matter
* It takes just over "mg" to accelerate from rest going up, but just under
mg to accelerate downward, so going up should take more "effort" to go up
than down.
* At some angles, it is easier for your muscles to exert this "effort". It
seems to me this should be tougher near the top. At the very bottom it
takes no "effort", of course, because the forces are supplied by bones, not
muscles.
* For slow pull-ups, muscle fatigue is a factor. On the way up, the
muscles are fresher than on the way down, so the second half seems harder.
You can rest at the bottom, so the next pull-up starts out a little easier
again.
*Just hanging half way up should be about as tough as doing pull-ups: ie
you could do pull-ups or hang for about the same time. Hanging at the top
would take more effort. Hanging at the bottom takes no effort (other than
grip strength, which will eventually limit the time)
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Therefore, perception on upstroke is predicted to be
_more effort, (unless you do it so slowly that fatigue is a factor)__
perception on downstroke is predicted to be
__less___
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