Chapter 18 - Gravitational Fields Flashcards
what is gravitational field strength
gravitational force per unit mass on a small object placed at a point within the field
gravitational field pattern
straight lines towards the centre of mass, shows that gravity is an attractive force
what do closer radial field pattern lines mean
stronger gravitational field
how else can a gravitational field be modelled
uniform lines, drawn parallel to eachother
G value
6.672 x 10^-11
keplers first law
the orbit of a planet is an ellipse, with the sun at focus
keplers second law
a line segment joining a planet and the sun sweeps out equal areas during intervals of equal running time
keplers third law
t^2 = r^3
uses of satellite
gps, scientific research
geostationary satellites
- orbital period of 24 hours
- travel along the equator
- remain equidistant to the earth
what is gravitational potential
work done per unit mass to move an object to a point from infinity
escape velocity
velocity required to escaped a gravitational field
condition for escape velocity
kinetic energy of the object at the start must be equal to or greater than the gravitational potential energy required to lift it to infinity
why is there a negative sign in gravitational constant
to show the attractive nature of the force
escape velocity equation
sqaure root of 2GM/R
