# Chapter 1: Introduction

The laws of physics have basic quantities which must be clearly defined. The basic quantities are length (L), mass (M), and time (T). Common system is SI. Length standard is the meter, mass is the kilogram, and time is the second. Dimensional analysis treats dimensions as algebraic quantities to test the correctness of equations.

Measurements have uncertainty and the number of significant figures gives the accuracy of the measurement. When multiplying, dividing, adding or subtracting the least accurate number (lowest number of significant figures) determines the number of significant figures in the answer.

To convert from one unit system to another use the conversion factors at the front of the book and multiply by equivalent quantities arranging for algebraic cancelation to get the units you want.

Order of magnitude estimates, the nearest power of 10, are useful to see if more detailed calculations are needed or test if an answer makes sense.

There are two common sorts of coordinate systems: Cartesian (rectangular) (x vs y) and plane polar (distance and angle).

A quick review of trigonemtry for right triangles: sine = opposite over hypotenuse; cosine = adjacent over hypenuse; tangent = opposte over adjacent; and a2 + b2 = c2.

Finally there is a step-by-step guide to solving problems.