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Physics for Scientists
and Engineers
Introduction
and
Chapter 1
Physics
Fundamental Science
Concerned with the fundamental principles of the Universe Foundation of other physical sciences Has simplicity of fundamental concepts
Divided into five major areas
Classical Mechanics Relativity Thermodynamics Electromagnetism Optics Quantum Mechanics
Classical Physics
Mechanics and electromagnetism are basic
to all other branches of classical and modern
physics
Classical physics
Developed before 1900
Our study will start with Classical Mechanics
Also called Newtonian Mechanics or Mechanics
Modern physics
From about 1900 to the present
Objectives of Physics
To find the limited number of fundamental
laws that govern natural phenomena
To use these laws to develop theories
Express the laws in the language of
mathematics
Mathematics provides the bridge between theory
and experiment
Theory and Experiments
Should complement each other
When a discrepancy occurs, theory may be
modified
Theory may apply to limited conditions
Example: Newtonian Mechanics is confined to objects
traveling slowly with respect to the speed of light
Try to develop a more general theory
Classical Physics Overview
Classical physics includes principles in many
branches developed before 1900
Mechanics
Major developments by Newton, and continuing through the 18th^ century
Thermodynamics, optics and electromagnetism
Developed in the latter part of the 19th^ century
Modern Physics
Began near the end of the 19th^ century
Phenomena that could not be explained by
classical physics
Includes theories of relativity and quantum
mechanics
Quantum Mechanics
Formulated to describe physical phenomena at the atomic level
Led to the development of many practical devices
Time
Units
seconds, s
Defined in terms of the oscillation of radiation
from a cesium atom
See Table 1.3 for some approximate time
intervals
Reasonableness of Results
When solving a problem, you need to check your answer to see if it seems reasonable
Prefixes
Prefixes correspond to powers of 10
Each prefix has a specific name
Each prefix has a specific abbreviation
Prefixes, cont.
The prefixes can be used with any basic units
They are multipliers of the basic unit
Examples:
1 mm = 10-3^ m 1 mg = 10-3^ g
Basic Quantities and Their
Dimension
Dimension has a specific meaning – it
denotes the physical nature of a quantity
Dimensions are denoted with square
brackets
Length [L]
Mass [M]
Time [T]
Dimensions and Units
Each dimension can have many actual units
Table 1.5 for the dimensions and units of some
derived quantities
Dimensional Analysis,
example
Given the equation: x = ½ at^2
Check dimensions on each side:
Significant Figures
A significant figure is one that is reliably known
Zeros may or may not be significant
Those used to position the decimal point are not significant To remove ambiguity, use scientific notation
In a measurement, the significant figures include the
first estimated digit
