gravitational fields

What is a field

A region in which a body experiences a non-contact force

Similarities between gravitational and electrostatic forces

both follow inverse square law, use field lines to be represented, have equipotential surfaces

Differences between gravitational and electric fields

in gravitational fields, the force exerted is always attractive, while in electric fields the force can be either repulsive or attractive, electric force acts on charge, while gravtiational force acts on mass

gravitational field strength

the force per unit mass exerted by a gravitational field on an object

define gravitational potential

work done per unit mass against gravitational force to move an object from infinity to a given point

newton’s law of gravitation

the magnitude of the gravitational force between two masses is directly proportional to the product of their masses and inversely proportional to the square of the distance between them

gradient of gravitational potential to distance graph

negative of gravitational field strength

area under gravitational field strength to distance graph

gravitational potential difference

Kepler’s third law

the square of the orbital period is directly proportional to the cube of the radius

escape velocity

the minimum velocity it must travel at, in order to escape the gravitational field at the surface of a mass, occurs when kinetic energy is equal the gravitational potential energy

synchronous orbit

where the orbital period of the satellite is equal to the rotational period of the object that is orbiting and in the same direction of rotation

geosynchronous orbit

a synchronous orbit around the earth, has a period of 24 hours, does not orbit over the same spot

geostationary orbit

a geosynchronous orbit which orbits directly above the equator, and has a circular orbit, appears stationary in the sky which is good for TV and telephone signals as you don’t have to alter the plane of an aerial or transmitter

low orbit satellites

travel faster so smaller orbital periods,useful for monitoring the weather making scientific observations about places which are unreachable

coulomb’s law

the magnitude of the force between two point charges in a vacuum is directly proportional to the product of their charges and inversely proportional to the square of the distance between them

gravitational and electric force on subatomic particles

the magnitude of electrostatic forces between subatomic particles is magnitudes greater than the magnitude of gravitational forces

electric field strength

the force per unit charge on a positive test charge placed at that point

(absolute) electric potential

the potential energy per unit charge of a positive point charge at that point

electric potential difference

the energy needed to move a unit charge between two points