# Warm-Up Exercise 39

## Due 12:15 pm, Wed 28 Nov 2012

Physics 123, Fall 2012

Reading assignment: 39.5

The Lorentz transformation equations relate the space and time coordinates of "events". What is an "event"? Give some examples.

An "event" is something that happens at a particular place, at a particular time. Examples: * A teacher slams a book on a table * My wife opens up our mailbox * A star goes supernova * The light from the supernova first reaches an astronomer's eye

The Lorentz transformation equations relate the coordinates of events occuring in different "frames of reference". What is a "frame of reference"? Give some examples.

For our purposes, a frame of reference is a viewpoint moving at a constant velocity. Examples: * Dr Colton in his spaceship * People on earth watching him leave * People of Zyzyz, awaiting his arrival

The Lorentz transformation equations are given as Eqn 39.11 and Eqn 39.12 (reverse transformation) (8th edition). Why are the equations for y and z so trivial?

The equations assume all of the relative motion is in the x-direction.