Gravitational and Electric Fields Flashcards
What is gravitational potential
The work done per unit mass to move an object from infinity to a point in the field
What is the units for gravitational potential
Joules per kilo gram
What is gravitational potential at infinity
Zero
What is Law of Gravitation
There’s an attractive force between two particles which is directly proportional to the product of the two masses and inversely proportional the the distance squared
What kind of force is produced by gravitational field
Attractive
What is gravitational field strength
The force per unit mass
What’s an equipotential
A point at which the gravitational/electric potential is the same, moving along it would cause no change in energy
What is the relationship between time period and radius
T squared is dp to r cubed
When is an orbit classed as low
When it’s 180-2000km above the earth
What’s an advantage of low orbit satellites
They are cheaper to get into orbit and require less powerful transmitters
What’s a disadvantage of low orbit satellites
They need multiple to maintain full coverage
What are low orbits used for and why
Imagine, spying and weather because they are closer so have a higher resolution .
They are also used for communications
What’s a geostationary satellite
An satellite with an orbital period the same as the earth rotational period therefore it stays stationary relative to the earth
Where must a geostationary orbit be in relation to the earth
Above the equator
What are geostationary satellites used for?
Tv and phone signals so that receivers don’t need to constantly change angle
What is important about the energy of an orbiting satellite
The total energy, (kinetic and potential) is the same, for circular orbits they kinetic and potential are always constant
What is gravitational potential difference
The energy needed to move a unit mass in a gravitational field
What is the area under a g/r graph
The change in gravitational potential
What is the shape of a gravitational potential against distance
Under the x axis the graph is a curve with decreasing gradient
What is the escape velocity
The velocity at which an objects kinetic energy is equal to its gravitational potential energy, so it’s the velocity is just be traveling at to escape a gravitational field
What’s an electric field
A region in which particles with a charge will experience a non contact force
What is coloumbs law
The force is proportional to the produc of the charges and inversely proportional to r2
What are the assumptions for coloumbs law
They are two point charges in a vacuum
What is electric field strength
The force per unit of positive charge
