Gravitational Fields
Define 'Gravity'
A universal attraction between any 2 masses
Give the formula for gravitational force
F = -GMm/r²
G = gravitational constant
Define a 'Gravitational Field line'
A line that indicates the direction of the gravitational force that would act on a test mass in a field
Define a 'Test Mass'
A mass small enough to not affect the shape of a gravitational field with its own gravity
Define 'Gravitational field strength'
The gravitational force per unit mass
Give 2 of the gravitational field strength equations
g = F/m
g = -GM/r²
Define a 'Perihelion'
The closest point to the sun in orbit
Define a 'Aphelion'
The furthest point from the sun
What is Keplars 1st Law?
The orbit of every planet is an elipse with the sun at one of the foci
What is Keplars 2nd Law?
A line segment joining a planet & the sun sweeps out equal areas during intervals of time
What is Keplars 3rd Law?
The square of the orbital period of a planet is directly proportional to the cube of its average distance from the sun
How long do 'Geostationary Satelites' take to orbit a planet & which direction does it travel?
- 1 day/ 24hours
They travel in the same direction as the earth rotation(along the equatorial plane)
Define a 'Satelite'
An object that orbits another object
Give 2 uses of 'Geostationary Satelites'
- Telecommunications(e.g. TV broadcasts)
- Surveying(e.g. weather)
Give the formula for 'Orbital speed'
v = √GM/r
Define 'Gravitational potential'
The work done per unit mass to move an object to that point from infinity
Give the formula for Gravitational potential
V = -GM/r
What does a negative Gravitational potential show
The work done per unit mass to remove an object from a field
Define 'Gravitational Potential Energy'
The work done to move a mass to a point in a field from infinity
Give the formula for GPE
E = -GMm/r
Give the fromula for Escape velocity
v = √2GM/r