Gravitational Fields Flashcards
(17 cards)
What is a gravitational field?
A region where a test mass will feel an attractive force towards a mass.
What do the field lines of a gravitational field represent?
Direction of force felt on a test mass in that field.
What is the type of force in gravitational fields?
Attractive.
What does the ‘M’ in the radial grav field strength represent?
Mass of objet creating the field.
How do you know which mass field lines are pointing to?
Always point towards centre of mass you’re describing.
What law do radial field lines follow?
Inverse square law.
What is gravitational potential?
Work done per unit mass to move a test mass from infinity to that point in the field.
What are the units for gravitational potential?
J/kg
What does the gradient of a V(grav potential) - r graph represent?
Field strength.
What does the area under a g(field strength) - r graph represent?
Gravitational potential.
What is a satellite?
A body that orbits another body in space.
What is Kepler’s third law?
The square of the time period of an orbit is proportional to the cube of the radius.
What is a geosynchronous orbit?
Body orbits above the equator, remains in same position above Earth’s surface. T = 24 hours.
What is a synchronous orbit?
Orbit period is equal to average rotational period of planet, rotates in same direction as planet.
How high up above the Earth’s surface does a geostationary satellite orbit?
36000km.
What is the total energy of a satellite?
- (GMm) / 2r
What is escape velocity?
Velocity required to remove an object from a gravitational field.
