COLLEGE PHYSICS (1401) CHAPTER 1 INTRODUCTION Dr. P TURAGA

WHAT IS PHYSICS? It is the study of nature or the physical world. WHY DO WE HAVE TO STUDY PHYSICS?

 PHYSICS IN EVERYDAY LIFE: What experience do you have with physics in your everyday life? Where do you “see” physics in your everyday life?

MECHANICS Kinematics Dynamics Kinematics describes motion of the objects without cause of motion. Dynamics describes motion of the objects with cause of motion.

Fundamental Quantities and their dimensions: Mechanics uses 3 fundamental quantities.  Length [L] – associated with “space”  Mass [M] – associated with “matter”  Time [T] – associated with “time”  Other physical quantities can be constructed from these three.

UNITS To communicate the result of a measurement for a quantity, a unit must be defined Defining units allows everyone to relate to the same fundamental amount

SystemLengthMassTime SI or MKSMeterKilogramSec CGSCentimeterGramSec US Customary or FPS FootSlug or Pound Sec SYSTEM OF UNITS

PREFIXES Prefixes correspond to powers of 10 Each prefix has a specific name Each prefix has a specific abbreviation

Generally used prefixes: PrefixPower of 10 kilo (k) mega(M) giga (G) centi (c) milli (m) micro (µ) nano (n)

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 Example: Analyze the equations x=vt and x=vt 2 ? Dimensional Analysis

There is uncertainty in every measurement, this uncertainty carries over through the calculations. Need a technique to account for this uncertainty – which is measured by using significant figures. Uncertainty in Measurements

Significant Figures It indicates the precision of a quantity A significant figure is a reliably known digit RULES: All non-zero digits are significant Final and ending zeros written to the right of the decimal point are significant Zeros on the right of a decimal point or left of a number are not significant When there is no decimal point, the final zeros are meaningless

Unit Conversions When units are not consistent, you may need to convert to appropriate ones Units can be treated like algebraic quantities that can “cancel” each other

Coordinate Systems Coordinate system consists of – A fixed reference point called the origin, O – Specified axes with scales and labels – Instructions on how to label a point relative to the origin and the axes Types of coordinate systems – Cartesian (rectangular) – Polar

Trigonometry SOH CAH TOA

Pythagorean Theorem r 2 = x 2 + y 2 To find an angle, you need the inverse trig function For example,  = sin = 45°