Physics 101: Lecture 2, Pg 1 Lecture 2: Introduction to Physics 101 Chapter 1 : The Conversion of Units (1.3) Trigonometry (1.4) Scalars and Vectors (1.5)

Physics 101: Lecture 2, Pg 2 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 Sears Tower 4.5 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

Physics 101: Lecture 2, Pg 3 Time: IntervalTime (s) Age of universe 5 x Age of Grand Canyon 3 x years 1 x 10 9 One year3.2 x 10 7 One hour3.6 x 10 3 Light travel from Earth to Moon1.3 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

Physics 101: Lecture 2, Pg 4 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

Physics 101: Lecture 2, Pg 5 Conversion of Units l Example: Distance Buffalo – Andromeda Nebula given in ly. What is the distance in km ? 1. Conversion factor: 1 ly=9.5 x km 2. Insert conversion factor: d= 2 x 10 6 ly = 2 x 10 6 x 1 ly = 2 x 10 6 x 9.5 x km = 1.9 x km Remember: 10 a x10 b = 10 a+b 10 a /10 b = 10 a-b

Physics 101: Lecture 2, Pg 6 Example: l Speed limit on german autobahn is 130 kmh. What is the speed limit in mph ?

Physics 101: Lecture 2, Pg 7 Lecture 2, ACT 1 A very good fastball pitcher can throw the ball 100 mph. What is the ball speed in m/s? m/s m/s m/s correct

Physics 101: Lecture 2, Pg 8 Dimensional Analysis l Dimension indicates the nature of a physical quantity or the type of unit. Example: Dimension of distance is length : [L] Unit of distance is m, km, miles, … Note: Dimensions of left-hand side and right-hand side of an equation have always to be the same, e.g. when you start with a quantity of dimension length you have to finish with one of dimension length. Powerful check of your computation !

Physics 101: Lecture 2, Pg 9 Example: l x= ½ a t n. Find n ?

Physics 101: Lecture 2, Pg 10 Trigonometry Definition of sine, cosine and tangent: Right angle: Sin  = h o /h Cos  = h a /h Tan  = h o /h a Pythagorean Theorem: h 2 = h o 2 + h a 2

Physics 101: Lecture 2, Pg 11 Example: l A certain mountain road is inclined 3.1 degrees with respect to the horizon. What is the change in altitude (in meters) of the car as a result of its traveling 2.90 km along the road ?

Physics 101: Lecture 2, Pg 12 Scalars and Vectors

Physics 101: Lecture 2, Pg 13 Lecture 2: Units Dimensional Analysis Trigonometry Scalars and Vectors I strongly suggest that you try the example problems in the textbook. If you have trouble with any of them, please go to office hours for help!