PHYSICS Physics Greek word fusis meaning nature or natural things Physics Branch of science that studies natural Phenomena in terms of basic laws and quantities Concepts speed time weight force etc Measurements speed limit 55 miles hr 1 gallon of milk Laws Measurements obey laws F ma Predictions Laws are used to make predictions space crafts aeroplanes Design mobile phones iPhone televisions PHYSICS Physics predicts how nature will behave in one situation based on the results of experimental data obtained in another situation Example Newton s laws Rocket science Maxwell s equations Telecommunications 1 Why Physics Analytical problem solving skills can t treat a patient without it Three things to improve your grade Homework homework homework Try not to short circuit this part by getting too much help Chapter 1 Intro and Mathematical Concept Introduction All things follow strict physics laws All physics laws we know can be described with mathematics To the point that we impose our math on nature 2 1 1 Length mass and time UNITS Question 3 cats 2 dogs SI units Le Syst me International d Unit s Fundamental units Meter m length Kilogram kg mass Second s time Distance Length m Radius of visible universe 1 x 1026 To Andromeda Galaxy 2 x 1022 Average person 1 7 Diameter of hydrogen atom 1 x 10 10 Diameter of proton 1 x 10 15 Foot yard they are also length units but few use it 3 Interval Time s Age of universe 5 x 1017 Bullet crossing the room 5 x 10 3 Remember Neo in Matrix Light pulses used in UB lasers 1 x 10 13 Lifetime of top quark 4 x 10 25 Object Mass kg Milky Way Galaxy 4 x 1041 Earth 6 x 1024 Physics student 7 x 101 Dust particle 1 x 10 9 Neutrino 1 x 10 38 Pounds few use it Meter distance traveled by light during a time interval of 1 299 792 458 second Kilogram a specific block of platinum iridium alloy kept in France Second 9192631700 oscillations of radiation from the cesium atom not easily affected 4 1 3 Dimensional analysis Symbols used to specify dimensions of length mass and time are L M and T are often used to denote the dimensions of physical quantities L M and T Dimensional analysis can be used to check if you messed up a problem Example Dimension of distance is length L Dimension of time T It is given to you that Velocity Length time Therefore the dimensions of velocity are L T 5 1 3 Dimesional Analysis L length M mass T time Is the following equation dimensionally correct x L 1 2 vt 2 L 2 T T L T 1 5 Conversion of units When units are not consistent you may need to convert to appropriate ones Units can be treated like algebraic quantities that can cancel each other See the inside of the front cover for an extensive list of conversion factors Example 1 inch 2 54 cm 15 0 in 2 54 cm 1 in 38 1 cm 6 THE CONVERSION OF UNITS 1 ft 0 3048 m 1 mi 1 609 km 1 hp 746 W 1 liter 10 3 m3 7 1 5 Conversion of Units Example Distance of Buffalo Andromeda Nebula given in light years ly 2 x 106 ly What is the distance in km 1 Conversion factor 1 ly 9 5 x 1012 km Units in problem solving The World s Highest Waterfall The highest waterfall in the world is Angel Falls in Venezuela with a total drop of 979 0 m Express this drop in feet Since 3 281 feet 1 meter it follows that Length 979 0 meters 3 281 feet 1 meter 3212 feet 8 Examples of various units measuring a quantity 1 7 Coordinate System Cartesian coordinate system Also called rectangular coordinate system x and y axes Points are labeled x y 9 Plane polar coordinate system Origin and reference lines are noted Point is distance r from the origin in the direction of angle ccw from reference line Points are labeled r Both coordinates 10 1 8 Trigonometry sin cos tan opposite side hypotenuse adjacent side hypotenuse opposite side adjacent side More Trigonometry Pythagorean Theorem r 2 x2 y 2 To find an angle you need the inverse trig function for example sin 1 0 707 45 Be sure your calculator is set appropriately for degrees or radians 11 Example Problem Example Problem An airplane travels 450 km due east and then travels an unknown distance due north Finally it returns to the starting point by traveling 525 km How far did the airplane travel in the north direction 12