SVSU PHYS 106C Keen Chp 3

Focus

either of the two points interior to an ellipse that defines its shape. The sun is always at one focus of a planet's elliptical orbit

first law of planetary motion (kepler)

the principle stating that planets more on elliptical orbits with the sun at one focus

semimajor axis

half of the long axis of an ellipse

semiminor axis

half of the short axis of an ellipse

eccentricity

a measure of the roundness of an ellipse, calculated as a ration: the distance from the ellipse's center to its foci, divided by the length of the semimajor axis

second law of planetary motion (kepler)

The principle stating that the line connecting a planet to the sun will sweep out equal areas of its orbit in equal times

conservation of angular momentum

the principle whereby the rotational speed of an object that spins or orbits a central point increase as the distance from the center decreases and vice versa

orbital period

the time an object takes to complete on revolution of an orbit

third law of planetary motion (kepler)

the principle stating that the square of a planet's orbital period (in years) equals its average orbital radius (in AU) cubed (p^2=r3)

Galilean moons

the 4 largest moons of Jupiter: io, Ganymede, Callisto, and Europa

Nebulosity

clouds in space

Force

an interaction between two bodies that, if unbalanced, can change their speed and/or direction of motion

Velocity

rate of change in position per unit of time

speed

an object's change in position per unit of time

acceleration

an object's change of velocity per unit of time

mass

a quantity of matter that is related to an object's resistance to changes in velocity, measured in kg,

inertia

an object's resistance to change in velocity

inertial law (issac newton 1st)

the principle stating that objects in motion and constant velocity along a straight line continue that way unless acted on by a net force

force law ( 2nd newton)

the principle stating that the change in an object's velocity due to an applied net force is in the same direction as, and directly proportional to, the force but inversely proportional to the object's mass

reaction law (3rd newton)

the principle stating that for every applied force, there is an equal and opposite force

net force

the sum of all forces acting on an object

momentum

the mass of an object multiplied by its velocity. Only the application of a force can change an object's momentum

gravity

an attractive force between any two massive bodies that depends on the product of the bodies' masses and the inverse square of the distance between them

universal law of gravity

the dependence of the force of gravity between two objects as the product of their masses multiplied by newton's constant divided by their distance of separation squared

constant of nature

a term that does not change from one situation or time to another. The value of a constant of nature must be measured to be determined

inverse square law

a relationship whereby a quantity (ex. gravity) decreases in proportion to the square of a variable (ex. distance) as the variable increases

weight

the downward force that gravity produces on an object

centripetal acceleration

acceleration involving a force that keeps an object moving on a circular path. The acceleration is directed toward the path's center of curvature

centrifugal force

the illusion of outward force when an object is moving on a curved path

orbital velocity

the velocity required to keep a body in orbit around another body

escape velocity

the velocity required to escape the pull of a massive body's gravity