Gravitational Fields CIE A-Level Physics

the gravitational force per unit mass at that point

F = mg

A region of space where a mass will experience a force

any two masses attract each other with a force proportional ti

F = GmM/r²

g = GM/r²

The gravitational pull on a satellite provides the centripetal force to keep the satellite in orbit.

v² = GM/r

T² = 4π²r³/GM

• A satellite orbits the Earth directly above the equator.

• If the satellite orbits in the same direction as the Earth spins and has an orbital period of 24 hours, it will remain over the same point above the Earth’s surface.

• Used for communication satellites.

Gravitational potential at a point is the work done per unit mass in bringing a unit mass from infinity to that point.

Φ = -GM/r

Because as a mass is brought closer to M its gravitational potential energy decreases. (GPE is defined as zero at infinity)

Ep = -GMm/r