
equilibrium
experiencing zero net force

equilibrium position
When nothing is pushing or pulling on the spring, and the free end is in equilibrium at a particular position

stable equilibrium
the end of the spring when it naturally returns to its equilibrium position if it is stretched or compressed

Hooke's law
 The stiffer the spring and the farther you stretch it, the harder it pulls back
 F = kx
 restoring force = spring constant x distortion

spring constant
k, measure of the spring's stiffness

collision energy
kinetic energy absorbed during the collision

rebound energy
kinetic energy released during the rebound

coefficient of restitution
coefficient of restitution = rebound speed of ball / collision speed of the ball

vibrational node
points near each end of the bat that do not move when the bat vibrates

elastic collisions
bounces so perfect that all of the collision energy is stored and returned as rebound energy

inelastic collisions
collisions that fail to return some of the collision energy as rebound energy

centripetal acceleration
 "centerseeking"
 brings toward the center

Nicolaus Copernicus
 14731543
 Heliocentric theory
 start of modern astronomy
 delayed publication of his book till the year of his death

Galileo Galilei
 15641642
 championed heliocentric universe by observation
 telescope observations

Johannes Kepler
 laws of planetary motion
 used data of Tyco Brahe as postulate motion of planets

Kepler's laws
 1. planet orbits = ellipses
 2. area swept fro the sun to a planet is constant in time (conservation of angular momentum, speeds up closer to foci)
 3. the bigger the orbit, the longer it takes the planet to go around its orbit

geosynchronous orbit
 at 35,900km above the earth's surface
 orbits the earth every 24 hours, stays at same place above the earth

