Science Forums Biology Forum Molecular Biology Forum Physics Chemistry Forum (http://www.molecularstation.com/forum/)
-   Physics Forum (http://www.molecularstation.com/forum/physics-forum/)
-   -   rotation. why easier when greater r? (http://www.molecularstation.com/forum/physics-forum/37479-rotation-why-easier-when-greater-r.html)

 mumi 10-30-2005 09:49 AM

rotation. why easier when greater r?

throwing a ball on the object
why is it 'easier' to rotate the object
when acting on the point farther away
from the point of rotation
(with greater r) ?
i know it is connected with angular momentum and so on
but why is it so?
it seems to me that it must be because of the way
force/acceleration/momentum/whatever the best
is 'distributed' between the
points/particles/atoms/??
of the object but i cant
think of any good way to touch this subject.
could anyone help?

 mumi 10-30-2005 11:02 AM

rotation. why easier when greater r?

and what would that reason be?

 Steve Ralph 10-30-2005 12:00 PM

rotation. why easier when greater r?

The Principle of Moments (which has nothing to do with clocks)

sr

 mumi 10-30-2005 12:41 PM

rotation. why easier when greater r?

this lecture states the same in a different way but gives no reason.
you cant use A to prove A
this lecture assumes that you will mulitply by r but gives no reason why
sure the numbers are correct but that's hardly a reason.
as far as i can see to give a reson one would have
to describe forces (or whatever good word) acting
on and within the bolt.

 mumi 10-30-2005 12:47 PM

rotation. why easier when greater r?

and the wrench. even more important

 mumi 10-30-2005 01:54 PM

rotation. why easier when greater r?

you just said the same in a more mathematical way.

it's not a reason of any kind.

to give the reason you would have to arrive at

t = I*a

starting from

F = m*a

(and or course you cant use other angular

equations like L = r x p untill you get it from

linear one)

Finding out that you get a correct result by

multiplying force by some vector which

in some magical way happens to be equal to r

is not the explanation i am looking for.

 mumi 10-30-2005 02:10 PM

rotation. why easier when greater r?

ah and of course you cant use any other conservation
laws. only linear momentum.
everything else would be finding some magical equation
that somehow fits.

 mumi 10-30-2005 05:12 PM

rotation. why easier when greater r?

why? why is torque for a fixed force direct proportional to the distance
from the fulcrum?
it is still magic to me.

 Matalog 10-30-2005 07:14 PM

rotation. why easier when greater r?

"John Christiansen" <[Only registered and activated users can see links. Click Here To Register...]> wrote in message
the

A good question.

 mumi 10-30-2005 07:39 PM

rotation. why easier when greater r?

> Torque is by definition the product of the of the force and the distance

i am really speechelss here.
are you trying to help me or annoy me?
cause you are doing the other.