Formula for gravitational field strength at a point in a gravitational field

g=F/m

What are gravitational field lines like on the surface of the earth

Uniform

What do all gravitational field lines point towards

The centre of mass of the the object creating the gravitational field

Equation for Newton’s law of gravitation

F=-GMm/r^2

What is the value and units of G

6.67 x 10^-11

Nm^2kg^-2

What does the negative sign show in Newton’s law of gravitation

That it is an attractive force

What is the formula to find gravitational field strength in a radial field

g=-GM/r^2

Kepler’s first law

The orbit of a planet is elliptical with the sun at one of two foci

Kepler’s second law

Line segment joining the planet and sun will sweep out equal areas during equal intervals of time

Keplers third law

T^2 is directly proportional to r^3

What is the astronomical unit

The mean distance between the earth and the sun

Equation to find the speed of an object in orbit

v^2 = GM/r

Equation for the pro oral time period of an object in orbit

T^2 =4pi^2r^3/ GM

Do keplers laws apply to smaller objects in orbit eg satellites and moons?

Yes

Sea of satellites

Communication, weather, pictures, research

3 conditions for a geostationary orbit

- be in orbit above the equator
- orbital period of 24 hours
- rotate same direction as earth

Symbol of gravitational potential

Vg

What is Vg defined as?

The work done per unit mass to move an object to that point from infinity

Is gravitational potential scalar or vector

Scalar

Equation for gravitational potential

Vg= -GM/r

Why is Vg always negative

Work is done to move one object away from another. Vg at infinity is a maximum of 0, so all values is negative as work is done to move it away from that point

Equation for gravitational potential energy in a uniform gravitational field

Ep=mgh

Equation for gravitational potential energy in a radial field

E=mVg

Equation for escape velocity

v^2=2GM/r