AST 220 Midterm Exam Questions with
Correct Answers
ptolemaic model The geocentric model of the universe developed by Ptolemy in about
150 AD
semimajor axis Half the distance across the long axis of an ellipse; in this text, it is usually
refered to as the average distance of an orbiting object, abbreviated a in the formula for kepler's
third law.
theory See A model of some aspect of nature that has been rigorously tested and has
passed all tests to date.
acceleration The acceleration of a falling object. On earth, the acceleration of gravity,
designated by g, is 9.8 m/s^2
unbound orbits Orbits on which an object comes in toward a large body only once, never
to return; unbound orbits may be parabolic or hyperbolic in shape.
Bound orbits Orbits on which an object travels repeatedly around another object; bound
orbits are elliptical in shape.
Conservation of angular momentum The principle that, in the absence of net torque
(twisting force), the total angular momentum of a system remains constant.
, force Anything that can cause a change in momentum.
kinetic energy Energy of motion.
mass A measure of the amount of matter in an object.
momentum The product of an object's mass and velocity.
newton's laws of motion Three basic laws that describe how objects respond to forces.
orbital energy The sum of an orbiting object's kinetic and gravitational potential energies.
potential energy Energy stored for later conversion into kinetic energy; includes
gravitational potential energy, electrical potential energy, and chemical potential energy.
radiative energy Energy carried by light; the energy of a photon is Planck's constant times
its frequency, or h x f
speed The rate at which an object moves. its units are distance divided by time, such as
m/s or km/hr
Correct Answers
ptolemaic model The geocentric model of the universe developed by Ptolemy in about
150 AD
semimajor axis Half the distance across the long axis of an ellipse; in this text, it is usually
refered to as the average distance of an orbiting object, abbreviated a in the formula for kepler's
third law.
theory See A model of some aspect of nature that has been rigorously tested and has
passed all tests to date.
acceleration The acceleration of a falling object. On earth, the acceleration of gravity,
designated by g, is 9.8 m/s^2
unbound orbits Orbits on which an object comes in toward a large body only once, never
to return; unbound orbits may be parabolic or hyperbolic in shape.
Bound orbits Orbits on which an object travels repeatedly around another object; bound
orbits are elliptical in shape.
Conservation of angular momentum The principle that, in the absence of net torque
(twisting force), the total angular momentum of a system remains constant.
, force Anything that can cause a change in momentum.
kinetic energy Energy of motion.
mass A measure of the amount of matter in an object.
momentum The product of an object's mass and velocity.
newton's laws of motion Three basic laws that describe how objects respond to forces.
orbital energy The sum of an orbiting object's kinetic and gravitational potential energies.
potential energy Energy stored for later conversion into kinetic energy; includes
gravitational potential energy, electrical potential energy, and chemical potential energy.
radiative energy Energy carried by light; the energy of a photon is Planck's constant times
its frequency, or h x f
speed The rate at which an object moves. its units are distance divided by time, such as
m/s or km/hr
