College Physics

Chapter 1Introduction

Science is a Philosophy It is not science without data It is not science without

measurement errors (somehow) It is not science unless it can be

reproduced (objectivity) Math is like the grammar of

science

Fundamental Quantities and Their Dimension Length [L] Mass [M] Time [T]

other physical quantities can be constructed from these three

Systems of Measurement Standardized systems

agreed upon by some authority SI -- Systéme International

1960 by international committee main system used in this text also called “mks” units

cgs – Gaussian system US Customary

nits of common usage

Prefixes Metric prefixes correspond to

powers of 10 Each prefix has a specific name Each prefix has a specific

abbreviation See table 1.4

Structure of Matter

Dimensional Analysis Technique to check the

correctness of an equation Dimensions (length, mass, time,

combinations) can be treated as algebraic quantities add, subtract, multiply, divide

Both sides of equation must have the same dimensions

Uncertainty in Measurements There is uncertainty in every

measurement, and uncertainty carries over through calculations

Lab uses rules for significant figures to approximate the uncertainty in calculations

Conversions Units must be consistent (time=time) Units carry value! (1 m = 100 cm) You can manipulate words in equations

just like you manipulate numbers Example:

Cartesian coordinate system

Also called rectangular coordinate system

x- and y- axes Points are labeled

(x,y)

Plane polar coordinate system Origin and reference

line are noted Points labeled (r,) Point is distance r

from the origin in the direction of angle , (counterclockwise from reference line)

Trigonometry Review

More Trig Pythagorean Theorem

To find an angle, you need the inverse trig function for example,

Be sure your calculator is set appropriately for degrees or radians

Must beware of quadrant ambiguities

Polar Coordinates Example Convert the

Cartesian coordinates for (x,y) to Polar coordinates (r,)

How High Is the Building? Determine the height of the building

and the distance traveled by the light beam

Problem Solving Strategy