Introduction to Physics The Science of Physics Expectations: 1.Learn about the branches of physics. 2.Learn useful tools for working with measurements and data.

What is Physics? Objective: 1.Identify activities and fields that involve the major areas within physics.

The Topics of Physics Goal of physics = use a small number of basic concepts, equations, and assumptions to describe the physical world Physics principles can be used to make predictions about a broad range of phenomena. Any problem that deals with temperature, size, motion, position, shape, or color involves physics.

Areas within Physics Quantum Mechanics Relativity Electromagnetism Optics Waves Thermodynamics Mechanics Physical Science: science of matter & energy Chemistry: matter & its changes Physics: forces & energy

Measurements in Experiments Objectives: 1.List basic SI units and the quantities they describe. 2.Convert measurements into scientific notation. 3.Distinguish between accuracy and precision. 4.Use significant figures in measurements and calculations.

Numbers as Measurements Measurements must include a number and a unit. The description of what kind of physical quantity is represented by a certain measurement is called dimension. There are 3 basic dimensions: length, mass, and time.

Numbers as Measurements SI is the standard measurement system for science. The system uses 7 base units that describe a single dimension. Examples:length = meter mass = kilogram time = second

Numbers as Measurements Prefixes are used to accommodate large and small values. PowerPrefixAbbreviationPowerPrefixAbbreviation atto-a10 -1 deci-d femto-f10 1 deka-da pico-p10 3 kilo-k nano-n10 6 mega-M micro-μ10 9 giga-G milli-m10 12 tera-T centi-c10 15 peta-P

Numbers as Measurements Reminders: Measurements must be expressed in units that match the dimensions of that quantity. Measurements used in calculations should also have the same units. Practice A on page 15.

Accuracy and Precision Careful measurement is important in physics, so we have to consider the accuracy and precision of all measurements. Accuracy – how close a measurement is to the correct/accepted value Precision – degree of exactness of a measurement (depends on the tool used)

Accuracy and Precision When indicating precision we use significant figures (digits in a measurement that are know with certainty plus the first digit that is uncertain). Using scientific notation is the best way to account for significant figures.

Accuracy and Precision Rules for Determining Whether Zeros are Significant Figures RuleExamples 1. Zeros between other nonzero digits are significant. a.50.3 m has three significant figures. b s has five significant figures. 2. Zeros in front of nonzero digits are not significant. a kg has three significant figures. b ms has one significant figure. 3. Zeros that are at the end of a number and also to the right of the decimal are significant. a g has four significant figures. b kg has seven significant figures. 4. Zeros at the end of number but to the left of a decimal are significant if they have been measured or are the first estimated digit; otherwise they are not significant. a.1000 m has one significant figure. b.20 m has one significant figure.

Accuracy and Precision Rules for Calculating with Significant Figures Type of CalculationRuleExample addition or subtractionGiven that addition and subtraction take place in columns, round the final answer to the first column from the left containing an estimated digit multiplication or divisionThe final answer has the same number of significant figures as the measurement having the smallest number of significant figures. 123 X

The Language of Physics Objectives: 1.Distinguish between conventions for abbreviating units and quantities. 2.Use dimensional analysis to check the validity of equations.

Evaluating Physics Equations Physics equations are only valid if they can be used to make correct predictions about situations. Dimensional analysis is one way to distinguish between valid and invalid equations. This procedure makes use of the fact that dimensions can be treated as algebraic quantities.