ch01 notes wo animations.pdf - 8/29/19 Physics Ch...

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Physics
Ch 1:Concepts of Motion Goals
• Models
• Describing Motion & Vectors
o Using diagrams, graphs, pictures
o Key quantities that describe motion
§ Time, Distance/Displacement, Speed/Velocity, Acceleration
• Physics problem solving strategies
• SI unit system & Conversion
• Scientific Notation & prefixes
• Interpreting Data
o Precision & uncertainty
Physics
• Most fundamental
of all natural sciences
• Deals with structure
& behavior of matter
• Concerned with discovery of fundamental
laws of nature (describable in mathematical
terms) & application of these laws to detailed
study of all physical phenomena
o 1061 covers Mechanics & Oscillations

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Historical
• “Astronomy was first science EVERYWHERE
o Where are we? When is it? How/Why?
• 1600s — Galileo & Newton — Mechanics
• 1700s-1800s — Thompson, Day, Joule — Heat
• 1800s — Maxwell — Electricity
• Early to mid 1900s — Einstein, Schrödinger,
Dirac, etc — QM
• Mid 1900s to present— various — lasers,
supercond, fusion, fission, semiconductors,
chaos, black holes, Higgs, dark matter, dark
energy, exoplanets, quantum computing
Machu Picchu Winter Solstice
Eclipse 2017

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Galileo Principle
• Recognize scientific problem exists;
• State hypothesis: educated guess about problem;
• Predict consequences of hypothesis;
• Perform experiments or make observations to see if
predictions occur;
• Formulate simplest general rule that organizes
hypothesis, predictions & experimental results into
theory.
Models and Theories
What is Science?
Models and Theories
• “All of Physics is either impossible or trivial. It
is impossible until you understand it, and
then it becomes trivial.”
— Sir Ernest Rutherford
• Once someone (Newton, Einstein, you?)
isolates simples laws from complex systems
they are understandable

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Word Problems – Set Up
• Read problem first to see what are you
looking for
• Read each phrase to determine what
quantities are given or implied & what sort of
thing they measure
o Not just number, but what sort of thing is it
• Decide whether you need to convert units
• What relevant model(s) are applicable
Word Problems – Solving
• Sketch the problem
• Choose useful coordinate system
o Useful meaning that it aligns with some aspect of
the physics that is going on
• Write the problem algebraically using
symbols both for knowns and unknowns
• Solve algebraically for each quantity before
putting in numbers
Word Problems – Checking
• Keep extra sig fig for intermediate values, but
round off final answer to correct # sig fig
• Make sure you list units and sign
• Check for reasonableness
o Not crazy big, small, sign, direction, etc.