Physics 1201W Lecture 1 Tuesday, September 8

Physics I – Mechanics “Big Picture” Allows you to understand and describe the physical world using relatively simple models and reasoning (useful for later in your career) Gives you experience in solving multi-step problems involving mathematics & logic Gives you experience in communicating technical information Gives you experience in relating causes & effects (experiment!)

Physics I – Mechanics “Details” Mechanics: – Kinematics – Dynamics – Momentum – Energy – Rotational Motion Statics Oscillations

Chapter 1: Units fundamental units: Everything in (classical) mechanics can be expressed in terms of fundamental units: – Length L – Mass M – Time T For example: – Speed - units L / T (i.e. miles per hour). – Force - units ML / T 2.

Units: Length DistanceLength (m) Radius of visible universe 1 x To Andromeda Galaxy 2 x To nearest star 4 x Earth to Sun1.5 x Radius of Earth6.4 x 10 6 Willis (Sears) Tower4.5 x 10 2 Football field1.0 x 10 2 Tall person 2 x 10 0 Thickness of paper 1 x Wavelength of blue light 4 x Diameter of hydrogen atom 1 x Diameter of proton 1 x

Units: Time IntervalTime (s) Age of universe 5 x Age of Grand Canyon 3 x years 1 x 10 9 One year 3.2 x 10 7 One hour 3.6 x 10 3 Light travel from Earth to Moon 1.3 x 10 0 One cycle of guitar A string 2 x One cycle of FM radio wave 6 x Lifetime of neutral pi meson 1 x Lifetime of top quark 4 x

Units: Mass ObjectMass (kg) Milky Way Galaxy 4 x Sun 2 x Earth 6 x Boeing x 10 5 Car 1 x 10 3 Physics Student 7 x 10 1 Dust particle 1 x Top quark 3 x Proton 2 x Electron 9 x Neutrino 1 x

Chapter 1: 1-D Motion

Position vs. Time

Average vs. Instantaneous Velocity Instantaneous velocity, v: slope of tangent to x vs. t graph at a given instant

Average vs. Instantaneous Velocity Instantaneous velocity, v: slope of tangent to x vs. t graph at a given instant