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Interactive Notes Chapter 1 Holt Physics Mrs. Broczkowski Spring 2014 Name:__________________ Date:___________________ Section 1: What is Physics? Check off the areas of science that you have studied so far in your high school science experience. What makes Physics different from some other types of science? How is it similar? ______________________________________________________________ _____________________________________________________________________ The goal of physics is to use a small number of basic _______________,____________ and __________________to describe the physical world. These physics principles can then be used to make _______________about a broad range of phenomena. Physics discoveries often turn out to have unexpected practical applications and serve to advance _______________________. Consider several careers that may interest you. Which areas within physics relate to your career? List the 7 areas of physics that we will consider in this course. 1.____________________________ 2. ____________________________ 3. ____________________________ 4. ____________________________ 5. ____________________________ 6. ____________________________ 7. ____________________________ The Scientific Method: Physics, like other sciences is based on the _______________ _______________. Make ___________ and collect _______ that lead to a question. Formulate and objectively test the _____________ using experiments Interpret ___________and revise the hypothesis if necessary. State ________ in a form that can be ____________ by others. Models Physics uses ______________that describe phenomena. A __________is a pattern, plan, representation, or description designed to show the structure or workings of an object, system, or concept. A set of particles or interacting components considered to be a distinct physical entity for the purpose of study is called a ________________. Consider a basketball – To analyze the motion of the ball, we will isolate the objects that affect its motion then draw a diagram that incudes only the motion. Draw the model below and then list the details that have been ignored in our diagram of motion. _________________, _____________, _________________ Hypotheses Models help scientists develop _______________________. A __________________is an explanation that is based on __________scientific research or observations and that can be _________________. The process of simplifying and modeling a situation can help you determine the relevant details and devise the hypothesis. Demo: Galileo’s Hypothesis Description 10 pennies dropped together vs. 1 penny dropped at the same time 10 coffee filters dropped together vs. 1 coffee filter dropped at the same time 10 pennies dropped in water together vs. 1 penny dropped in water at the same time. Observation Explanation Experiments: Models help guide _________________ ______________. A hypothesis must be tested in a _________________experiment. A controlled experiment tests only one factor at a time by using a comparison of a ______________ group with an ________________ group. Section 2:Measurements in Experiments In SI, the standard measurement system for science, there are seven ______units. Each base unit describes a single_____________, such as length, mass, or time. The units of length, mass, and time are the meter (m), kilogram (kg), and second (s), respectively. Prefixes may be used with base units – why? ________________________________________________________________ Page 12 in your text lists common prefixes. You will need to refer to this for homework and laboratory problems. You do not need to memorize them. _________ units are formed by combining the 7 base units with multiplication or division. There are other acceptable units with SI to describe quantities outside of the m-kg-s system. Examples of derived units we will use in physics are: Symbol Name Quantity Derived Unit Equivalence °C Hz J N Pa Degree Celsius Hertz Joule Newton Pascal Temperature Frequency Work and Energy Force Pressure 1/s Kg-m2/s2 = N-m kg-m/s2 kg/m-s2 = N/m2 What do the derived units have in common? __________________________________________ When using units in calculations, ______________ and ____________must agree. Example Problem: (p 14 in text): A typical bacterium has a mass of 2.0 fg. Express this measurement in terms of grams and kilograms. Given: Unknown: Conversion Factors from the relationship, 1 x10-15 g = 1 fg Solution: *Note: For our calculators, enter 1 EE -15 to stand for 1 x10-15 Accuracy and Precision • ____________________is a description of how close a measurement is to the correct or accepted value of the quantity measured. • _________________is the degree of reproducibility of a measurement. It describes the limitations of the measuring device. • A numeric measure of confidence in a measurement or result is known as ________________________A lower uncertainty indicates greater confidence. What are some common sources of error that lead to uncertainty? These will be used to describe results in experiments this year! _____________________________________ _______________________________________________________________________ _____________ ________________ help to keep track of imprecision. The rules for determining if zeros are significant or not are listed on page 17 of your book. The rules for using sig figs in calculations are on page 19 of your text. You will need to review these as the year goes on. Do calculators keep track of sig figs for you? Discuss with a partner. Mathematics and Physics: Tables, Graphs and Equations will be used to make data easier to understand. Consider the table data above. 1.Were the data collected at regular time intervals? 2. According to the distances displayed in the table, did one of the balls appear to fall faster than the other one? 3.Did the golf ball travel the same distance during every time interval? 4. Sketch the graph of distance vs. time. Label axis with titles and units as we will do in laboratory this year. 5. What is the equation derived from this graph? _________________________. 6. What advantage does a graph of data give you? Variables and Units Physicists use _______________to describe measured or predicted relationships between physical quantities. _________________and other specific quantities are abbreviated with letters that are boldfaced or italicized. __________are abbreviated with regular letters, sometimes called roman letters. Two tools for evaluating physics equations are ___________________and order-ofmagnitude estimates. The first 3 variables that you must learn and recall are: Quantity Change in position Time interval mass Symbol Δx, Δy Δt m Units meters seconds kilograms Unit Abbreviation m s kg Notes Quiz: Complete these using your notes in preparation for the Chapter 1 Test. 1.What area of physics deals with the subjects of heat and temperature? A. mechanics B. thermodynamics C. electrodynamics D. quantum mechanics 2.What area of physics deals with the behavior of subatomic particles? F. mechanics G. thermodynamics H. electrodynamics J. quantum mechanics 3.What term describes a set of particles or interacting components considered to be a distinct physical entity for the purpose of study? A. system B. model C. hypothesis D. controlled experiment 4.What is the SI base unit for length? F. inch G. foot H. meter J. kilometer 5.A light-year (ly) is a unit of distance defined as the distance light travels in one year. Numerically, 1 ly = 9 500 000 000 000 km. How many meters are in a light-year? 10 A. 9.5 10 m 12 B. 9.5 10 m 15 C. 9.5 10 m 18 D. 9.5 10 m 6. If you do not keep your line of sight directly over a length measurement, how will your measurement most likely be affected? F. Your measurement will be less precise. G. Your measurement will be less accurate. H. Your measurement will have fewer significant figures. J. Your measurement will suffer from instrument error. 7. If you measured the length of a pencil by using the meterstick shown in the figure and you report your measurement in centimeters, how many significant figures should your reported measurement have? A. one B. two C. three D. four 8. A room is measured to be 3.6 m by 5.8 m. What is the area of the room? (Keep significant figures in mind.) F. 20.88 m 2 1 G. 2 10 m 1 2 H. 2.0 10 m 2 2 J. 21 m 9. What technique can help you determine the power of 10 closest to the actual numerical value of a quantity? A. rounding B. order-of-magnitude estimation C. dimensional analysis D. graphical analysis 10. Which of the following statements is true of any valid physical equation? F. Both sides have the same dimensions. G. Both sides have the same variables. H. There are variables but no numbers. J. There are numbers but no variables. The graph shows the relationship between time and distance for a ball dropped vertically from rest. Use the graph to answer questions 11–12. 11. About how far has the ball fallen after 0.20 s? A. 5.00 cm B. 10.00 cm C. 20.00 cm D. 30.00 cm . 12.Which statement best describes the relationship between the variables? F. For equal time intervals, the change in position is increasing. G. For equal time intervals, the change in position is decreasing. H. For equal time intervals, the change in position is constant. J. There is no clear relationship between time and change in position. 13. Determine the number of significant figures in each of the following measurements. A. 0.0057 kg B. 5.70 g C. 6070 m 3 D. 6.070 10 m 14. Calculate the following sum, and express the answer in meters. Follow the rules for significant figures. 2 (25.873 km) + (1024 m) + (3.0 10 cm) 15. Demonstrate how dimensional analysis can be used to find the dimensions that result from dividing distance by speed. 16. You have decided to test the effects of four different garden fertilizers by applying them to four separate rows of vegetables. What factors should you control? How could you measure the results? 17. In a paragraph, describe how you could estimate the number of blades of grass on a football field.