Corner Brook Regional High School

Transcription

1 Corner Brook Regional High School

2 Measurement and Calculations Significant Digits Scientific Notation Converting between Units Accuracy vs. Precision Scalar Quantities Distance Calculations Speed Calculations Distance-Time Graph Speed Time Graph Vector Quantities Displacement Calculations Velocity Calculations Acceleration Calculations Vector Diagrams

3 Chapter 9 Intro, 9.2, 9.5, 9.6, 9.7, 9.10 Chapter 10 Intro, 10.2, 10.3, 10.4, 10.7 Chapter 11 Intro, 11.1, 11.3, 11.5, 11.7

4 DEFINITION: The study of motion, matter, energy, and force. Branches include: MECHANICS (motion and forces) WAVES (sound and light) ENERGY (potential and kinetic, thermodynamics) MODERN (quantum physics, nuclear physics)

5 CERTAINTY Defined as the number of significant digits plus one uncertain (estimated) digit The last digit of any number is always UNCERTAIN, as measurement devices allow you to estimate. EXAMPLE: 2.75 m The 5 is uncertain

6 TAKE THE FOLLOWING MEASUREMENT and determine the certain digits and the uncertain digit. ANSWER:

7 1. EXACT VALUES EXACT VALUES have an INFINITE ( ) NUMBER of SIGNIFICANT DIGITS. TWO TYPES: COUNTED VALUES directly counted Ex: 20 students, 3 dogs, 5 fingers DEFINED VALUES always true, constant measures Ex: 60 s/min, 100 cm/m, 1000 m/km

8 2. ZEROS ALL NUMBERS in a value are SIGNIFICANT EXCEPT LEADING ZEROS, and TRAILING ZEROS WITH NO DECIMAL. VALUE NUMBER OF SIG FIGS

9 3. MULTIPLYING and DIVIDING WHEN MULTIPLYING(x) and DIVIDING(/), ANSWER has SMALLEST NUMBER of SIGNIFICANT DIGITS. EXAMPLE: 6.15 x 8.0 = =

10 4. ADDING AND SUBTRACTING WHEN ADDING(+) and SUBTRACTING(-), ANSWER has SMALLEST NUMBER of DECIMAL PLACES. EXAMPLE: =

11 5. ROUNDING When ROUNDING, if the number is 5 or GREATER, ROUND UP. Remember, round only once! VALUE 61.3 s m/s 36.5 km 99.0 m/s min ROUND to 2 SIG FIGS

12 A convenient way of expressing very large and small numbers. Expressed as a number between 1 and 10 and multiplied by 10 x (x = exponent). LARGE numbers exponent is # of spaces to the LEFT SMALL numbers NEGATIVE exponent is # of spaces to the RIGHT

13 ROUND THE FOLLOWING to 2 SIGNIFICANT DIGITS. VALUE SCIENTIFIC NOTATION 100 m 3500 s 926,000,000,000 h m s 0.1 m/s 2

14 DO THE 2 ATTACHED WORKSHEETS in your handout for homework.

15 BASE UNIT A unit from which other units may be derived, including units for the following: Length Mass Time metres, m kilogram, kg second, s Temperature kelvin, K In science, we use SI BASE UNITS, from the INTERNATIONAL SYSTEM OF UNITS. DERIVED UNIT A unit which is derived from base units. Ex: m/s

16

17 METRIC PREFIXES Values placed in front of the base units. PREFIX SYMBOL FACTOR giga G 10 9 mega M 10 6 kilo k 10 3 hecta h 10 2 deca da 10 1 SI BASE UNITS deci d 10-1 centi c 10-2 milli m 10-3 micro μ 10-6 nano n 10-9

18

19 To convert, using the following system: TO THE RIGHT multiply by 10 TO THE LEFT divide by 10 G M k h da SI BASE UNITS d c m μ n DIVIDE BY 10 MULTIPLY BY 10

20 EXAMPLES: 1.6 m = μm 340 N = hn

21 EXAMPLES: 1250 cm = km 4.7 Gg = ng

22 In addition to using metric prefixes, we also convert between SI UNITS and other accepted systems of measurement. Here are some helpful CONVERSION FACTORS you should know when studying MOTION: 1 km = 1000 m 1 h = 3600 s 1 m/s = 3.6 km/h

23 CONVERT THE FOLLOWING: 23 min = h 0.47 h= s

24 CONVERT THE FOLLOWING: 4.5 km/h = m/s 30.2 m/s = km/h

25 DO THE 2 ATTACHED WORKSHEETS in your handout for homework.

26 POINTS to REMEMBER: Whatever you do to ONE SIDE of an EQUATION, you must do to the OTHER SIDE. Do not move the item you are trying to isolate. Move EVERYTHING ELSE!!! Do the opposite to move a variable. For example, to move a variable that is multiplied, divide by it.

27 Rearrange the following equations to solve for the variable indicated: a = v Solve for v. t

28 y = mx + b Solve for m.

29 DO THE ATTACHED WORKSHEET in your handout for homework.

30 Accuracy measures how close a measurement is to an ACCEPTED or TRUE VALUE. It is expressed as a PERCENT VALUE (%). Often, poor accuracy is a result of flaws in equipment or procedure. EXAMPLE: Accepted Value a g = 9.80 m/s 2 Experimental Value a g = 9.50 m/s 2 Accuracy = 96.9 %

31 Precision measures the reliability, repeatability, or consistency of a measurement. It is expressed as the accepted value ± a discrepancy. Often, poor accuracy is a result of flaws in techniques by the experimenter. EXAMPLE: Accepted Value a g = 9.80 m/s 2 Experimental Value a g = 9.50 m/s 2 Precision = 9.80 m/s 2 ± 3.06

32 EXAMPLE: Describe the ACCURACY and PRECISION of each of the following results. PRECISION: ACCURACY: PRECISION: ACCURACY: PRECISION: ACCURACY: PRECISION: ACCURACY:

33 QUALITITATIVE DESCRIPTIONS Describing with words. These descriptions are made using the 5 senses. Example: colour of a solution odor of a chemical product sound of thunder QUANTITATIVE DESCRIPTIONS Describing with numbers (i.e., quantities). These descriptions are made by counting and measuring. Example: height of a building speed of an airplane