Gravitational Fields Flashcards
What is Gravity?
Define Gravitational field strength (g)
The universal attractive force which acts between all matter.
force per unit mass
Newton’s Law of Gravitation
Magnitude of the gravitational force between two masses is directly proportional to the product of the masses and is inversely proportional to the square of the distance between them.
Define Gravitational Potential (at a point in the field) (V)
The work done per unit mass when moving an object from infinity to that point.
What is the gravitational potential difference? ∆V
energy needed to move a uni mass between two points
What is an equipotential surface?
A surface in which every point on the surface has the same potential. SO no work is done when loving along it.
Gravitation potential (V) is inversely proportional to…
the distance between the centres of the two objects (r)
What is Kepler’s third law?
the square of the principal period (T) is directly proportional to the cube or the radius (r)
The total energy of an orbiting satellite is… and is…
total energy= Ek +Ep
always kept constant
Compare the Ep and Ek of a lower orbit to a higher one.
A lower orbit (smaller m) has less potential energy and more kinetic energy than a higher orbit (bigger r).
Equation for T^2 of orbital object
T^2= 4π^2/GM × r^3
What is a geosynchronous orbit?
An orbit with a period of 24 hours.
What is escape velocity? + equation?
minimum velocity it must travel at, in order to escape the gravitational field at the surface of a mass.
v = √2GM/r
