# Sidereal frame and conservative force.

1. Aug 12, 2009

### Gwilim

Briefly describe a sidereal frame of reference, and then state Newton's laws of motion

I can't find sidereal in the index of my textbook, but my googling leads me to conclude that it's something to do with fixed stars. I'm not sure if a sidereal frame is also an inertial frame. Newtons laws are easy enough, but I get the feeling I'm not being asked for the classical formulations, but rather to append 'with reference to an inertial frame' or the like to the end.

State the properties satisfied by a conservative field of force, and then derive the energy equation for a particle of constant mass m moving under the influence of such a force

Umm, help?

2. Aug 14, 2009

### tiny-tim

Hi Gwilim!

"sidereal" simply means fixed relative to the stars …

it's more inertial than a laboratory frame!

(because it doesn't pretend that the Earth isn't spinning. )
Go on, start … what are the properties satisfied by a conservative field of force?

3. Aug 14, 2009

### Gwilim

So what would be acceptable wording in an exam?

"A sidereal frame of reference is one which uses fixed stars as a frame of reference"?

Seems a bit, uhh, self referential?

I don't know :( I hear it's something about 0 curl but I don't think I'm expected to know what curl is so that can't be the answer they're looking for. Can't you just tell me?:uhh: