Gravitational Fields Flashcards
What will any object with a mass experience when put in the gravitational field of another object?
An attractive force
What is a gravitational field?
It is a region where a body experiences a force, force field
What does an object need to have in order to experience a significant gravitational field?
A large mass
What types of gravitational fields can you have?
Uniform
Radial, when a mass is moved further away, the force it experiences decreases
What do gravitational field lines show?
The strength of the field at each point, where there is a higher density of field lines, there is a stronger field
what happens close to the Earth’s surface?
Over a small local region, the force is almost uniform as the lines are nearly parallel
Newtons law of gravitation?
Any two masses will attract each other with a force F, which is proportional to the product of their masses and inversely proportional to the square of the distance between them.
What type of law is the law of gravitation?
It is an inverse square law so when R decreases, F increases, this is because it is radial so the force will be the same at any point at the surface.
What is a gravitational field strength?
It is the gravitational force per unit mass and acts towards the centre of the mass whose field is being described, it produces the centipetal force
What can the gravitational field strength be seen as?
The acceleration of the mass due to gravity or in an gravitational field
What type of gravitational fields do point masses have?
Radial
What type of law is radial gravitational fields part of?
It is the inverse square law because as R doubles, G decreases to a quarter of its original value
Are gravitational fields vectors or scalar?
They are vectors, you can add them up to find the combined effect of more than one object by taking one direction is positive and the other is negative and adding.
What is gravitational potential?
It is the gravitational potential energy that a unit mass at that point would have, it is numerically equal to the work done in taking a unit mass from infinity to that point
What is gravitational potential at the surface of earth?
It is negative and then increases with distance from the earth.
When would gravitational potential be zero?
At any infinite distance from the mass
What is gravitational potential difference?
It is the distance needed to move a unit mass from one point to another
What happens when you move an object?
There is work done against gravity
What happens due to friction?
The radius of the orbit will decrease, causing the total energy to decrease which means that it is moved to a lower orbit and the velocity of the object increases
What happens when there is a greater radius on the satellite’s orbit
It will travel slower and it will take longer to complete one orbit
What is always constant for an orbiting satellite?
The total energy, it has both kinetic and potential energy, this is all constant because height and speed are constant for circular orbit.
What occurs in elliptical orbits?
The satellite will speed up as its height decreases this means that potential energy and kinetic energy change however the total energy is always constant
Features of a geosynchronous orbit?
It will orbit directly over the equator, staying in the same point relative to a certain point on earth, so will appear stationary. They travel at the same angular speed as a so are useful for TV and telephone signals as they do not have to alter the receiver to keep up with the signals. Their orbits take exactly one day.
What are polar orbits useful for?
Weather satellites, as they travel around the earth multiple times each day. They could also be used for surveillance.
