Gravitational field Flashcards
What is a gravitational field
An area around a mass of which a gravitational force acts
What do gravitational field lines show
The direction of the force on a small test mass
describe two essential features of a sattelite for it to be geostationary
- must stay above the same point above the equator
- it’s orbit needs to be the same time period as one rotation of the earth
what is a radial field?
a field in which the field lines are straight and converge or diverge as if from a single point
what is a uniform field?
a region where the field strength is the same in magnitude and direction at every point in the field
what is gravitational potential?
the work done per unit mass
when moved from infinity to a point
what is newtons law of gravitation
- the force of attraction between two point masses
- proportional to product of masses
- inversely proportional to square of distances between them
describe two advantages of geostastionary orbit
- offers uninterupted communication between transmitter and reciever
- steerable dish is not nessacery
describe and explain what happens to speed of a sattelites orbit when it get’s closer to the planet it is orbiting
- speed increases
- loses potential energy but gains kinetic energy
why do rockets launched from the earth’s surface not have to achieve escape velocity
- energy is continually added in flight
- they are not escaping the gravitational field
what is gravitiaional field strength
the force per unit mass on a small mass placed in a gravitional field
what is a satellite
any smaller mass which just orbits a much larger mass
what is escape velocity
the minimum velocity an object must be given to escape from the planet when projected vertically from the surface
what is an equipotential
line or surface in a field alogn which the electric or gravitational potential is constant
what is a low orbiting satellite
any satellite which orbit between 180 and 2000km above the earth
what is a synchronous orbit
an orbit when an orbiting object has an orbital period equal to the rotational period of the object it’s rotating
in an eliptical orbit how does the kinetic and potential energy of a satellite change
it will speed up as it’s orbital radius decreases so kinetic energy increases as potential energy decreases.Total energy remains constant
what is the key difference between electric and gravitational fields
gravitational forces are always attractice
electrostatic forces can be attractive or repulsive.
why is gravitational potential negative
as work is done against the gravitational field to move the object out of it
