Physics Study of Matter and Energy• The goal of physics is to use a small number of basic concepts, equations, and assumptions to describe the physical world.• These physics principles can then be used to make predictions about a broad range of phenomena.Physics discoveries often turn out to have unexpected practical applications, and advances in technology can in turn lead to new physics discoveries.
The Branches of PhysicsTopic Subject ExamplesMechanics Describing the motion of Cars, trains, Sky divers, objects planets, spinning objectsThermodynamics Heat and Temperature Movement of fluids, heating and cooling objectsElectromagnetism Electricity, Magnetism, Charges, flowing and Light electrons, circuits, magnets, electromagnetsVibrations and Waves Sound and Light Springs, pendulums, sound, color, lasersModern Relativity, Quantum Atoms, the building Mechanics, Nuclear blocks of atoms, their physics behavior
The Scientific Method • There is no single procedure that scientists follow in their work. However, there are certain steps common to all good scientific investigations. • These steps are called the scientific method.
Numbers as Measurements• In SI, the standard measurement system for science, there are seven base units.• Each base unit describes a single dimension, such as length, mass, or time.• Derived units are formed by combining the seven base units with multiplication or division. For example, speeds are typically expressed in units of meters per second (m/s).
Other Units/Definitions You Should KnowVolume (liter, l, cm3) How much space an object takes upWeight (Newton’s, N) How gravity affects your massDensity (g/cm3) Mass per unit volume D = M/V
SI PrefixesPower Prefix Abbreviation10-12 pico- p10-9 nano- n10-6 micro- μ10-3 milli- m10-2 centi- c103 kilo- k106 mega M
Common Conversions you should know1in = 2.54 cm5280 ft = 1 mile3ft = 1 yd.621 mi = 1 km1 hour = 3600 seconds
Sample ProblemA typical bacterium has a mass of about 2.0 fg. Express this measurement in terms of grams and kilograms.Given: mass = 2.0 fgUnknown: mass = ? g mass = ? kg
Sample Problem, continuedNotice the two conversion factors below are inverses (flipped.) 1×10 –15 g 1 fg and 1 fg 1× 10 –15 gOnly the first one will cancel the units of femtograms to give units of grams. 1×10 –15 g (2.0 fg) = 2.0 ×10 –15 g 1 fg
Sample Problem, continuedTake the previous answer, and use a similar process to cancel the units of grams to give units of kilograms. 1 kg (2.0 ×10 –15 g) = 2.0 ×10 –18 kg 1×103 g
Graphing• Independent variable you control (x-axis)• Dependent variable depends on the ind. (y-axis)10 points on graphs1. Title y vs x (dependent vs independent)2/3 Label both axis correctly4/5 Units on axis6/7 Scale for both axis even8 Dots with circle in correct place9 Best fit line10 Ruler
Inertia Balance Lab• Inertia the property of matter that opposes any change in its state of motion (mass is a measure of inertia)• Amplitude the distance the object travels away from the equilibrium• Period The time for one complete back and forth swing. (T=# of s/# of vibrations)