Gravitational Fields Flashcards
What is a gravitational field?
It is the force field surrounding a mass.
What are gravitational field lines?
They are the path a small test mass placed in a gravitational field follows.
What is the formula for gravitational field strength?
g=F/m.
What is gravitational field strength?
It is defined as the force per unit mass exerted on a test mass placed in a field.
What is a force field?
It is a region in which a body placed feels a non-contact force.
What direction is the force towards?
The force is towards the centre of the object creating the gravitational field as the gravitational force is always attractive.
Whats the formula for the gravitational force between two objects?
F=Gm1m2/r^2/.Where r is the distance between the the two centres of the spheres.
What is newtons law of gravitation?
The gravitational force between two point objects is always attractive,directly proportional to the product of their masses and directly proportional to 1/the distance between them squared.
What is the formula for gravitational potential using G?
It is equal to -GM/r.jkg^-1.
What is the potential gradient?
Its the change in potential/distance moved.
How can you find g using the potential gradient?
g=-potential gradient.
What is gravitational potential?
It is the work done required to move an object from infinity to that point.
What is the formula for the work needed to move from one point of gravitational potential to another.
w=m x delta v.Tis can be substituted to show the gpe of an object equals GMm/r.
What are equipotententials?
They are surfaces of constant potential.The equipotentials are always perpendicular to the field lines.
How to derive keplers third law?
Find an expression for v by equating centripetal force to gravitational force.Then V=2pir/T where T is time period.Rearrnage to make T the subject and you will derive the law.
How is the radius of a satellites orbit related to its speed and time period?
The greater the radius the slower the speed and the longer it will take for the orbit to be completed.
Whats the formula for gravitational potential energy?
Ep=GMm/r.
What is a geostationary orbit?
This is an example of a synchronous orbit meaning it has the same orbital period as the planet it is orbiting.It remains at the same point above the planet as its angular speed of rotation is equal to that of the planet it is rotating.They also travel in the same direction as the planet.Their orbital radius is 42000km which is 36000km above the surface of the earth.Equator.Plane of equator.
What is a low. orbiting satellite?
It is a high speed satellite that orbits at around 180-2000km above the earths surfacace.Low orbit imaging.
