Physics 101: Conceptual Physics About Me My office is in Science 356 Come say hello! Best place to ask questions is office hours WF 2-4PM, T 10AM-1PM, or by appointment Best way to contact me is email jfielder@sfsu.edu put Phys 101 in the subject line That s how we roll. http://www.physics.sfsu.edu/~jfielder/ Phys101S15.html Goals For This Class Help you develop: a basic understanding of the central ideas of physics the ability to solve basic problems using physics concepts a real-world perspective for how physics is connected to your daily life Enrollment Very Full! Prerequisites Administrative Stuff Lab (Physics 102) Textbook Mastering Physics Course ID: fielder 2-week free trial period Introductory assignment due soon! Register as soon as humanly possible Participation 15% of your final grade is class participation Short writing assignments Group activities Voting If you miss class, you cannot make up the participation credit 1
Homework About 1 assignment per week Problems from textbook Working in groups is encouraged, but the work you turn in must be your own. Homework is 30% of your final grade (so each assignment is worth about 2%) Exams 3 midterms (15% each) and a final (25%) Lowest midterm score is dropped multiple choice and some short problems Exam dates are not flexible DO NOT MISS EXAMS! THERE ARE NO MAKEUPS! Grades Homework 30% Participation (15 x 1% each) 15% Midterms (top 2 x 15% each) 30% Final Exam 25% Syllabus Questions? I do not offer extra credit, but exams and overall grades may be curved. If you need to talk about your grade in detail, email me to make an appointment. The Montillation of Traxoline It is very important that you learn about traxoline. Traxoline is a new form of zionter. It is montilled in Ceristanna. The Ceristannians gristerlate large amounts of fevon and then brachter it to quasel traxoline. Traxoline may well be one of our most lukized snezlaus in the future because of our zionter lescelidge. (attributed to the insight of Judy Lanier) The Montillation of Traxoline It is very important that you learn about traxoline. Traxoline is a new form of zionter. It is montilled in Ceristanna. The Ceristannians gristerlate large amounts of fevon and then brachter it to quasel traxoline. Traxoline may well be one of our most lukized snezlaus in the future because of our zionter lescelidge. Directions: Answer the following questions in complete sentences. Be sure to use your best handwriting. 1. What is traxoline? 2. Where is traxoline montilled? 3. How is traxoline quaselled? 4. Why is it important to know about traxoline? 2
A Commonly Held Incorrect Model of a Student s Conceptual Framework A Commonly Held Incorrect Model of Teaching and Learning tabla rasa If a bowling ball and a baseball are both dropped from the same height at the same time, which one will reach the ground first? A. The bowling ball, because it has more mass B. The baseball, because it has less mass C. The bowling ball, because it is larger in size D. They will reach the ground at about the same time E. None of the above Class Discussion: What do you think science is? Evaluating and expressing our notions about science Find a partner or two, and answer the following questions after discussing them and coming to an answer you can all agree on. 1. What are the differences between a hypothesis, a theory and a law in science? 2. What is required for an experiment or observation to be scientific? 3. Do scientists ever get it wrong? If so, do they try to fix it, and how? Laws, Theories, and Hypotheses What is the difference between a hypothesis, theory, and law? How do scientists use these words differently from the public? 3
The Scientific Method 1. Which problem do you want to solve? 2. Form hypothesis 3. Design experiment and make predictions 4. Perform experiment/observations 5. Do the data support the hypothesis? ->Revise or reform hypothesis based on results So what is Science? Questions Models Tests & Predictions Evaluation Building up to a set of rules : Laws or Theories This course covers the basics: Physics can be BIG! Different branches of physics: motion, matter, heat, light, sound, electricity, magnetism, nuclear reactions, and relativity How to solve basic problems Not just the what but the why behind it (or as much of the why as we currently understand ) SI Units: The Système International or mks Length: meter (m) Mass: kilogram (kg) Time: second (s) Force: newton (N) Energy: joule (J) Current: ampere (A) Temperature: kelvin (K) Metric System (Units of Length) Everything is based on the meter (m) 1 kilometer (km) = 1000 m = 10 3 m 1 centimeter (cm) = 0.01 m = 10-2 m 1 millimeter (mm) = 0.001 m = 10-3 m 1 nanometer (nm) = 0.000000001 m = 10-9 m Good estimates: 1 meter is about 3.3 feet 1 inch is 2.54 centimeters 5 miles is about 8 kilometers 4
Why unit conversions are important! Units & Conversions Example: How many seconds are in a year? Scientific Notation & Significant Figures How precisely do we know a number? Example: How many days are there in a year? Which of the following correctly expresses 186,000 m/s in scientific notation, to three sig figs? A. 18.600 x 10 4 m/s B. 186.0 x 10 3 m/s C. 1.86 x 10 5 m/s D. 1.86 x 10 3 m/s An American football field is 300 feet long (not counting the end zones). Roughly how long is this in meters? A. About 91 meters B. About 99 meters C. About 910 meters D. About 9,900 meters Newton s 1 st Law & Inertia (Chapter 2) Get out your voting cards for reading check. 5
Which scientist used inclined planes to study motion? A. Copernicus B. Aristotle C. Newton D. Galileo E. None of these scientists used inclined planes to study motion. Which of the following is the SI unit of force? A. pound B. newton C. kilogram D. meters per second Which of the following best describes what inertia is? A. The tendency of objects to resist changes in their motion B. The tendency of objects to stay standing still C. The tendency of objects to slide downhill D. The tendency of objects to slow down after they re pushed Which of the following explains what is meant by net force? A. The strength of the force of gravity acting on an object B. The strength of all forces combined acting on an object EXCEPT gravity C. The strength of all forces combined acting on an object Newton s 1 st Law Newton s 1 st Law An object at rest will remain at rest and an object in motion will remain in uniform motion unless acted upon by a force. Object at rest (not moving) then No force on object Uniform motion: constant speed in a straight line. Also called the law of inertia Uniform motion then 6
So what is inertia? Typical Force Sizes The tendency of an object to keep doing what it s already doing Amount of inertia depends on the amount of mass. Careful, though: Inertia is not the same thing as mass, and inertia isn t a force either! Net Force When several forces act on an object, the forces combine to produce a net force or total force. If the individual forces are all in the same direction, the size of the net force is just the sum of the individual forces. Use arrows to symbolize force vectors: length of arrow shows size of force, direction of arrow shows direction of force Combining Forces Direction counts! If two forces are in the SAME direction, they ADD together If two forces are in the OPPOSITE direction, the smaller one SUBTRACTS from the larger one 3 N 5 N 8 N Vector Notation When handwritten, use an arrow A When typing, use boldface: A To write just the magnitude use italics: A The Σ symbol (capital sigma) means the sum of. To describe adding up all the forces on an object, write ΣF or ΣF How much net force is acting on the box? A. 0 N B. 5 N C. 10 N D. 15 N E. 20 N 7