Re: Lecture Notes

[Jim Green <JMGreen@SISNA.COM>]

Paul, I completely agree, but why would an oceanography professor say this
do you suppose.  I admit that I don't know much about oceanography, but
before I tell this person that s/he doesn't know much about physics, I
would like to know if there is any basis at all for this statement.  The
notes go on to say some other odd (read ridiculous) things, but I resist
using the phrase "hot air" to a professor at a school of oceanography in
this casae.

Other comments????

Jim Green

At 16:15 29 06 2000 , you wrote:
> ----- Original Message -----
> From: "Jim Green" <JMGreen@SISNA.COM>
> To: <PHYS-L@lists.nau.edu>
> Sent: Thursday, June 29, 2000 4:33 PM
> Subject: Lecture Notes
>
>
> > This morning I was surfing about and came across the following taken from
> a
> > lecture note page. I am not comfortable with this wording. Comments???
> >
> > To understand the tide-generating force you need to understand centripetal
> > force. Centripetal force that keeps the Earth-moon system together is
> provided
> > by gravity.
>
> Well, gravity certainly supplies the centripetal force that keeps the
> Earth-moon system together as they revolve around their common CM.
>
> > All particles of the Earth follow circles of equal radius as they rotate
> in the
> > Earth-moon system.
>
> This is not correct. Earth particles move in circular paths as the Earth
> rotates, but their motion in space is more complex as the rotating Earth
> revolves about the Earth-moon CM.
>
> > The centripetal force required to keep each particle in an identical orbit
> is the
> > same and is directed toward the center of the orbit.
>
> This is true in the restricted case of particles in identical orbits. But
> that includes only particles having a common latitude and a common distance
> from Earth's center.
>
> Paul O. Johnson

Jim Green
mailto:JMGreen@sisna.com
http://users.sisna.com/jmgreen