1. Chapter 1 - The Science of Physics Section 1.1 - What is Physics?

2. What is Physics? Physics is the study of the physical world Goal: To use a small number of basic concepts, equations, and assumptions to describe the physical world Physics is EVERYWHERE!!

3. The atom and its parts Behavior of submicroscopic particles Quantum mechanics Particle collisions, particle accelerators, nuclear energy Particles moving at any speed, including very high speeds Relativity Electrical charge, circuitry, permanent magnets... Electricity, magnetism, and light Electromagnetism Mirrors, lenses, color, astronomy LightOptics Springs, pendulums, soundSpecific types of repetitive motions Vibrations and wave phenomena Melting and freezing processes, engines... Heat and temperatureThermodynamics Falling objects, friction, weight, spinning objects Motion and its causesMechanics ExamplesSubjectsName Areas within Physics Topics of Physics

5. The scientific Method SCIENTIFICALLY PROVEN X Make observations And collect data that Lead to a question Formulate Hypothesis Test Hypothesis: Experiments Interpret Results, and revise the hypothesis if necessary State Conclusions in a form that can be evaluated by others

6. The Scientific Method A police investigator comes to the scene of an accident Observation? Hypothesis? Experiments/tests? Interpret/revise hypothesis? Conclusions?

7. Models describe only a part of reality a replica or description designed to show the structure or workings of an object, system, or concept Physicists decide which parts are important and which aren’t Physicists use Models

8. E.g. Basketball System: a set of items or interactions considered a distinct physical entity for the purpose of study. In the basketball example you are studying the ball and its motion Other factors such as color, size, spin, aren’t considered in the model

9. Physicists use Models Review: A Model describes a part of reality The system is what you are studying

10. Galileo’s Hypothesis What was the Question? What was his hypothesis? How did he test his hypothesis?

11. Controlled Experiment Experiment involving manipulation of a single variable or factor In order to test a hypothesis, you must change one variable at a time

12. Chapter 1 - The Science of Physics Section 1.2 - Measurements in Experiments

13. Measurements in experiments Dimension: tells us what physical quantity we are dealing with. Three basic dimensions: Length Mass Time Units: tells us how much of that physical quantity we are talking about

14. SI standards In 1960, an agreement was made on seven base units We will deal with only three Second (s)Time Kilogram (kg)Mass Meter (m)Length UnitDimension

15. Prefixes SI uses prefixes to accommodate extremes The distance between stars is approximately 100 000 000 000 000 000 m The distance between atoms in a solid is approximately 0.000 000 001 m Mr. Samuel can’t even say those numbers You shouldn’t be expected to say them either These numbers are expressed in powers of 10. The distance between stars is approximately 1 x 10 17 The distance between atoms is 1 x 10 -9 m

16. Prefixes PowerPrefixAbbreviationPowerPrefixAbbreviation 10 -18 atto-a10 1 deka-da 10 -15 femto-f10 3 kilo-k 10 -12 pico-p10 6 mega-M 10 -9 nano-n10 9 giga-G 10 -6 micro-  10 12 tera-T 10 -3 milli-m10 15 peta-P 10 -2 centi-c10 18 exa-E 10 -1 deci-d

17. Converting Measurements Use conversion factor that will cancel with the units you are given to provide the units you need. The units to which you are converting should usually be in the numerator. It helps to cross out the units that cancel Lets PRACTICE

18. Practice 1A A human hair is approximately 50  m in diameter. Express this diameter in meters. A typical radio wave has a period of 1  s. Express this period in seconds A hydrogen atom has a diameter of about 10nm. Express this diameter in meters. Express this diameter in millimeters. Express this diameter in micrometers. The distance between the sun and the Earth is about 1.5 x 10 11 m. Express this distance with an SI prefix and in kilometers. The average mass of an automobile in the United States is about 1.440 x 10 6 g. Express this mass in kilograms

19. Accuracy vs Precision Accuracy is the closeness of measurements to the correct or accepted value of the quantity measured. Precision is the closeness of a set of measurements of the same quantity made in the same way.

20. Accuracy vs Precision

26. Accuracy suggests that the experiment has accounted for all factors that might affect the system being studied Precision lets us know that the experiment was done carefully in a controlled environment Accuracy vs Precision

27. Precision Precision describes the limitations of the measuring instrument

28. Significant Figures Significant figures are used in science to indicate precision Includes all the digits actually measured (18 cm), plus one estimated digit In the pencil example we can estimate that it is 0.2 cm past the 18 cm mark. Because 18.2 cm is an estimate, the true value is between 18.15 cm and 18.25 cm.

29. Significant Figures When last digit is a zero, it is impossible to tell how many significant figures there are. If we say 230 mm, is it between 225 mm and 235 mm or is it between 229.5 mm and 230.5 mm. We solve this by recording it in scientific notation by expressing it as a power of 10. If there are 2 significant figures we write it as 2.3 x 10 2 cm. If there are 3 significant figures we write it as 2.30 x 10 2 cm.

30. Rules for zeros

31. Rules for calculating sig figs

32. Rules for rounding Calculators do not pay attention to significant figures

33. Chapter 1 - The Science of Physics Section 1.3 - The Language of Physics

34. Mathematics and physics Mathematical tools are used to analyze and summarize observations in physics Tables, graphs and equations can make data easier to understand

35. Mathematics and Physics (change in position in meters) = 4.9 x (time of fall in seconds) 2

36. Mathematics and Physics Physicists use mathematics to describe measured or predicted relationships. between physical quantities in a situation Physicists use letters to describe specific quantities.  (delta) means “difference or change in”  (sigma) means “sum” or “total”.  y  t  

37. Mathematics and Physics

38. Dimensional Analysis Dimensional analysis can weed out invalid equations. Dimensions can be treated as algebraic quantities. The two sides of any given equation must have the same dimensions.

39. Dimensional Analysis How long does it take a car driving at 88 km/h to drive a distance of 725 km?

40. Order-of-magnitude estimations It is often useful to estimate an answer before solving the problem. This can be done with an order-of- magnitude calculation - determining the power of 10 closest to the actual numerical value. In the car example: The answer should be closer to 10 than to 1 or 100 8.2 h is the correct answer and fits this range