AST 101 Sept.20
Newton’s law of Gravity: The force of gravity between masses M and m is equal to
the product of their masses, times the gravitational constant G, divided by the
square of the distance between them
Mass: the total number of atoms something has.
Orbits: Why does the moon orbit, and not fall into the earth? Because the moon is
moving perpendicular to the force of gravity.
Minimum speed required to orbit: Vorbital.
An object moving under the influence of gravity alone is free fall.
Vcircular: bigger speed than Vorbital.
Escape speed is the speed at which something has to be thrown to escape earth’s
Vescape = 1.4 x Vcircular
Tycho Brahe charted the position of all the planets. Tycho’s student, Johannes