College Physics What’s it? *Physics studies the fundamental forces behind natural phenomena, and seeks universal laws governing the material world. * Physics is a cornerstone of modern science and technology.

*Physics is a major basis for understanding the inorganic world as well as the biological world including human bodies. *Application of physics to biomedical and clinical sciences has produced not only new knowledge vital to health care but also numerous powerful techniques for Today’s hospitals. College Physics Why bother to learn?

This course will help you to develop a comprehensive and quantitative understanding of physics. It will cover major contents of college-level physics and also try to introduce several medical physics topics. College Physics What about this course?

Textbook ： College Physics (2nd Edition) by Paul Peter Urone, published by Thomson Learning Grading ： Written exam Tutors: Yongkang Le, Senior Lecturer (Dr. rer. nat., University of Kaiserslautern, Germany) TA: Dakang Liu Speaking hours: Physics Building Rm. 342 Tel: Time:? Course Webpage: College Physics Course Information

Part 1. Introduction: Physical quantities, units, and mathematical preparation Part 2. Kinematics Part 3. Dynamics: Newton’s law of motion Part 4. Linear & angular momentum Part 5. Work and energy College Physics Course contents

Part 6. Temperature, heat Part 7. Oscillatory motion, waves & sounds Part 8. Electrical charge, field, & energy Part 9. Magnetism Part 10. Electromagnetic waves & optics Part 11. Advanced topics: fluid physics, atomic & nuclear physics College Physics Course contents

College Physics Chapter 1 Introduction

VIP Words In science, there is only physics. All the rest is stamp collecting.— Ernest Rutherford Experiments are the only means of knowledge at our disposal. The rest is poetry, imagination. — Max Plank When you can measure what you are speaking about and express it in numbers, you konw something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meager and unsatisfactory kind. — Lord Kelvin

Theories and Experiments The goal of physics is to develop theories based on experiments A theory is a “guess,” expressed mathematically, about how a system works The theory makes predictions about how a system should work Experiments check the theories’ predictions Every theory is a work in progress

Fundamental Quantities and Their Dimension Length [L] Mass [M] Time [T] For statics and dynamics, other physical quantities can be constructed from these three

Units To communicate the result of a measurement for a quantity, a unit must be defined Defining units allows everyone to relate to the same fundamental amount

Systems of Measurement Standardized systems agreed upon by some authority, usually a governmental body SI -- Systéme International agreed to in 1960 by an international committee main system used in this text also called mks for the first letters in the units of the fundamental quantities

Systems of Measurements, cont cgs – Gaussian system named for the first letters of the units it uses for fundamental quantities US Customary everyday units often uses weight, in pounds, instead of mass as a fundamental quantity

Length Units SI – meter, m cgs – centimeter, cm US Customary – foot, ft Defined in terms of a meter – the distance traveled by light in a vacuum during a given time

Mass Units SI – kilogram, kg cgs – gram, g USC – slug, slug Defined in terms of kilogram, based on a specific cylinder kept at the International Bureau of Weights and Measures

Standard Kilogram

Time Units seconds, s in all three systems Defined in terms of the oscillation of radiation from a cesium atom

Approximate Values Table 1.3 in the text show approximate values for length, mass, and time Note the wide range of values

Prefixes Prefixes correspond to powers of 10 Each prefix has a specific name Each prefix has a specific abbreviation See table 1.2

Structure of Matter Matter is made up of molecules the smallest division that is identifiable as a substance Molecules are made up of atoms correspond to elements

More structure of matter Atoms are made up of nucleus, very dense, contains protons, positively charged, “heavy” neutrons, no charge, about same mass as protons protons and neutrons are made up of quarks orbited by electrons, negatively charges, “light” fundamental particle, no structure

Structure of Matter

Uncertainty in Measurements There is uncertainty in every measurement, this uncertainty carries over through the calculations need a technique to account for this uncertainty

Significant figures A method to keep track of the accuracy Definition Rules in calculation

Conversions 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 Example 1.1 Example:

Order of Magnitude Approximation based on a number of assumptions may need to modify assumptions if more precise results are needed Order of magnitude is the power of 10 that applies

Coordinate Systems Used to describe the position of a point in space Coordinate system consists of a fixed reference point called the origin specific axes with scales and labels instructions on how to label a point relative to the origin and the axes

Types of Coordinate Systems Cartesian Plane polar

Cartesian coordinate system Also called rectangular coordinate system x- and y- axes Points are labeled (x,y)

Plane polar coordinate system Origin and reference line are noted Point is distance r from the origin in the direction of angle  from reference line Points are labeled (r,)

Trigonometry Review hai’poti,nju:z

More Trigonometry Pythagorean Theorem To find an angle, you need the inverse trig function for example, Be sure your calculator is set appropriately for degrees or radians pai,Θægə’ri:ən

Problem Solving Strategy

Read the problem Identify the nature of the problem Draw a diagram Some types of problems require very specific types of diagrams

Problem Solving cont. Label the physical quantities Can label on the diagram Use letters that remind you of the quantity Many quantities have specific letters Choose a coordinate system and label it Identify principles and list data Identify the principle involved List the data (given information) Indicate the unknown (what you are looking for)

Problem Solving, cont. Choose equation(s) Based on the principle, choose an equation or set of equations to apply to the problem Substitute into the equation(s) Solve for the unknown quantity Substitute the data into the equation Obtain a result Include units

Problem Solving, final Check the answer Do the units match? Are the units correct for the quantity being found? Does the answer seem reasonable? Check order of magnitude Are signs appropriate and meaningful?

Problem Solving Summary Equations are the tools of physics Understand what the equations mean and how to use them Carry through the algebra as far as possible Substitute numbers at the end Be organized

Homework assignments 1 At page Problem 1.8, problem 1.9 Problem 1.17 Calculate the distance between P and G in the diagram of the PPT No. 29 Read § at Pages 14-25, do some exercises on your own selection