physics 100 lecture 2, may 14, 2010 n. alberding

Physics 100Lecture 2, May 14, 2010

N. Alberding

Mastering Physics

•Course ID is SFUPHYSICS100E

•Can buy stand-alone Mastering Physics codes at bookstore.

•http://www.masteringphysics.com

•Knight, Jones and Field, College Physics, 1st edition.

The Speed of Earth

•How fast does the surface of the earth move?

•To make it easy, assume we’re on the equator.

•Vancouver is at 50° N; how does that change the answer?

Puzzle

•You’ve been told that the earth rotates

•But it really looks like the sun goes around the earth

•Why believe what you’ve been told?

•Why doesn’t a ball come down far away when it’s tossed up in the air?

•Answer coming…..

Why Mathematics?

•Compact language

•Logic is embedded in the language.

•The Travellers’ Tale

•how non-mathematical language can confuse logic.

Kinematics

•Using math to describe motion

•Start with space

•Then do time….

Space

•What is distance?

•Operational Definition

•Define in terms of an operation that allows its measurement

Distance•Establish a standard “stick” for the

unit of distance.

•Measure how many sticks fit between two points.

•take the path that gives the smallest #

•Subdivide the stick into subunits for more precision.

The Metre•After the French revolution they

decided to use the earth as the standard

•hopefully neutral, no objections

•Define N. Pole to Equator = 10 000 000 m

•through Paris (not so neutral?)

•they actually measured the distance from Dunkirk (51°N) to Barcelona (41°N) and figured it out.

Triangulation