phys_CIRCULAR MOTION & GRAVITATION

uniform circular motion

an object moving in a circle at constant speed

-velocity is tangent to circle; direction changes continuously
-acceleration is perpendicular to velocity and points inwards towards the circle

centripital (radial) acceleration

acceleration in a circle; points inwards towards the center of the circle

Period (of a circle)

amount of time required for one complete revolution around the circle

*T

Frequency (of a circle)

# of revolutions per second
measured in Hertz

*f

Centripital force

Net force of a circle; points towards the center of the circle

Equation for Centripital force?

Use Newton's second law: Fnet = ma

Fnet of circle = (mv^2) / r

Newton's Law of Universal Gravitation

Every particle in the universe attracts every other particle in the universe;

-proportional to masses
-inversely proportional to square of distance between them

Kepler's Laws

Laws that govern the motion of planets

Kepler's First Law

The path of each planet about the sun is an ellipse with the sun at one focus. (An ellipse is the locus of points such that the sum of the distance to each focus is constant.)

Kepler's Second Law

Each planet moves such that an imaginary line drawn from the planet to the sun sweeps out equal areas in equal times.

Kepler's Third Law

The ratio of the squares of the periods of any two planets revolving around the sun is equal to the ratio of the cubes of their mean distances from the sun.

Centrifugal force

NONEXISTANT!!!! There is no such thing as center fleeing force

*appears to exist in non-inertial reference frames