Gravitational Fields 2. Non-uniform (radial) Fields

Physics and Chemistry for IG and A level

This post follows on from this earlier one which introduced Newton’s Universal Law of Gravitation.

An object with mass creates a gravitational field around it sucking mass towards it – like a whirlpool. Imagine a paper boat. It will always be pulled towards the centre of the hole.Screen Shot 2013-09-12 at 4.05.38 PM

The gravitational field strength (vector) g is defined as the gravitational force at a given point divided by the mass of an object at that point so g=F/m

On earth g = 9.81Nkg-1 (acc due to gravity). Slightly variable, equatorial r >polar r, thus g greater at the poles, neglecting the spin of the earth which will tend to reduce effective value.

g = constant near the Earth’s surface, falls as as we move away.

Gravitational field lines (parallel) are perpendicular to equipotential surfaces (zero change in GPE  when moving around on them, i.e, the field is conservative. The same work…

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