College Physics What’s it?

1. College PhysicsWhat’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.

2. College PhysicsWhy bother to learn? *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.

3. College PhysicsWhat about this course? 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 introduce several advanced medical physics topics.

4. College PhysicsCourse Information Textbook：College Physics(2nd Edition) by Paul Peter Urone, published by Thomson Learning Grading：Written exam Tutors: Zhisong Wang, Professor of Physics (Dr. rer. nat., University of Tübingen, Germany) Yongkang Le, Senior Lecturer (Dr. rer. nat., University of Kaiserslautern, Germany) Speaking hours: Friday 2 pm -3:30 pm Institute of Modern Physics Rm. 213(55664592)

5. College PhysicsCourse contents • 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

6. College PhysicsCourse 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

7. College Physics Chapter 1 Introduction

8. 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

9. Fundamental Quantities and Their Dimension • Length [L] • Mass [M] • Time [T] • other physical quantities can be constructed from these three

10. 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

11. 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

12. 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

13. 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

14. 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

15. Standard Kilogram

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

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

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

19. 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

20. 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

21. Structure of Matter

22. Uncertainty in Measurements • There is uncertainty in every measurement, this uncertainty carries over through the calculations • need a technique to account for this uncertainty • rules for significant figures to approximate the uncertainty in results of calculations (Page 13)

23. 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:

24. Examples of various units measuring a quantity

25. 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

26. 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

27. Types of Coordinate Systems • Cartesian • Plane polar

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

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

30. Trigonometry Review hai’poti,nju:z

31. 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

32. Problem Solving Strategy

33. 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

34. 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)

35. 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

36. 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?

37. 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

38. Homework assignments 1 • Page 26-27 • Problem 1.8, problem 1.9 • Problem 1.17 • Problem 1.37 (consult the text of Section 1.3)