# Physics Quiz 2/9

Torque

A measure of the force that can cause an object to rotate about its axis

Torque equation

T=Fr (r = distance from pivot point)

Clockwise rotation causes __________ torque

negative

counterclockwise rotation causes ________ torque

positive

rotational equilibrium

occurs when an object's net torque is zero

centripetal force

A force that causes an object to move in a circle

centripetal force equation

Fc=mv^2/r

Kepler's First Law

planets move in elliptical orbits with the sun at one focus (other focus is empty)

Kepler's Second Law

The radius from the sun to the planet sweeps out equal areas in equal times.

eccentricity

A relative measure of how elliptical an ellipse is. (distance from focus to focus)/length of the major axis

Kepler's Third Law

The ratio between the mean orbital radius (length of major axis) cubed to the orbital period squared is a constant for all planets (R^3/T^2 = Constant for all planets)

Gravity

A force of attraction between objects with masses.

fundamental forces

gravity, electromagnetic force, strong nuclear force, weak nuclear force

force of gravity

Fg = Gm1m2/r^2

G

6.67 x 10^-11

Orbital speed equation

V = ?Gmcentral/R

Au

distance from earth to sun

Equation for pendulum

T = 2? ?L/g