Gravitational Fields Flashcards
Define the gravitational field strength
the force per unit mass on a small test mass placed in the field.
What is a uniform field?
the gravitational field strength is the same in magnitude and direction throughout the field.
Define gravitational potential energy
the energy of an object due to its position in a gravitational field.
Define gravitational potential
the work done per unit mass to move a small object from infinity to a point in the field.
What are equipotentials?
surfaces of constant potential. no work needs to be done to move across an equipotential surface.
What is the potential gradient at a point?
the change of potential per metre.
how do g and the potential gradient compare?
gravitational field strength is always the negative of the potential difference.
Define Newton’s law of gravitation
the gravitational force between two point objects is always attractive. is proportional to the product of the masses of the object. is proportional to the inverse square of their separation.
What is the escape velocity?
the minimum velocity an object must be given to escape from a planet when projected vertically from the surface.
What is a satellite?
a mass that orbits a larger mass
What is Kepler’s law?
r^3 is proportional to T^2
What is a geostationary satellite?
orbits the earth directly above the equator and has a time period of exactly 24 hours. it therefore remains in a fixed position above the earths equator because it has exactly the same time period as the earth’s rotation.
