Physics Math Notes. A. Scientific Method Process used to ensure scientific precision and accuracy. 1. Problem State the question at hand.

Transcription

1 Physics Math Notes A. Scientific Method Process used to ensure scientific precision and accuracy Problem State the question at hand. 2. Hypothesis Best guess on what the experiment will produce.

2 2 3. Materials Items used for the experiment. 4. Procedure The method used to perform the experiment.

3 a. The experimenter must try to control all the variables of the experiment or the items or events that may affect the results. 3 b. The Control Group receives all the same stimuli as the Experimental Group except for 1 variable. c. The Experimental Group receives the 1 extra variable.

4 4 5. Observation The observable information obtained from the experiment. a. The experiment may use a Single Blind where the only the experimenter knows what they are testing. b. A Double Blind is when neither the experimenter nor the subject knows what they are testing for.

5 6. Conclusion- The results 7. Scientific Theory - Educated guess based on unproved assumptions to explain an event. ex Big Bang or Einstein - Stated Relativity Theory (E = mc 2 ). 8. Scientific Law - Based on experimentation. MAY BE CHANGED ex. falling objects and Aristotle vs. Galileo a. Conservation of Matter - Matter can neither be created nor destroyed. b. Conservation of Energy - Energy can neither be created nor destroyed but may be transferred. c. Conservation of Matter/Energy -Matter /energy can neither be created nor destroyed but may be transferred under normal conditions. 9. Data Any computations required to validate the results and measurement information used to describe the object or action. 5

6 6 B. Models A means to explain the fundamental properties of object. 1. Properties describes the characteristics of the object. 2. Referent - means to refer to, a familiar object used to describe a new object.

7 7 C. Experimental Factors 1. Parallax - Inaccurate measurement due to a poor angle. a. Optical Illusions

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13 13 2. Quality - uses no measurements. Such as color, smell, etc Quantity - uses measurements. Such as distance, temperature, et.

14 4. Accuracy - how well the measurement agrees with the standard thus, arrows that strike closer to the bulls eye are considered more accurate. 5. Precision - the degree of exactness to which a measurement can be reproduced thus arrows closely grouped are precise. 6. Note: measurements can precise, though not necessarily accurate and visa versa 7. For example a group of arrows could all be on the first ring which shows accuracy but they are spread all around the ring which is poor precision. 14

15 8. And a group of arrows could all be closely placed together which shows precision but they are all on the outside ring which is poor precision. D. Measurement Systems 1. Roman System 1 of several many measurements used in ancient times a. Cubit - distance of elbow to finger tip. b. Stadia - unit of length of once around the track English System - System used in the United States, was originally devised by Henry the VIII. a. Foot distance of 12 inches

16 3. Metric System - devised in 1791 by the French of Sciences Academy 16 Giga --Mega -- Kilo Hecto Deka BASE deci centi milli -- micro -- nano -- pico International System AKA SI, derived from Metric System (France) in 1960

17 a. Used World Wide b. Changes by units of 10 c. Based on water, 1ml = 1 cm 3 = 1 cc = 1 g d. Uses prefixes to change by tens e. Standard Units and Tools 5. Fundamental Units - 4 measurements that cannot be broken down. a. Distance - meter - meter stick, length that light travels in 1/ 299,792,458 seconds 17

18 b. Mass - gram balance c. Mass a measure of inertia of an object or amount of matter unaffected by gravity Matter 4 states of anything that has mass, takes up space and has inertia.

19 2. Inertia - an object at rest remains at rest, an object in motion remains in that straight line motion unless acted upon by an outside force. Newton s 1 st Law 19

20 3. Balance a device used to measure mass Weight - a unit of force measured in newtons, same as pounds, DO NOT confuse Weight with MASS. a. Weight is affected by gravity and it is greatest at North or South Pole or closer to earth s core and least at equator or up a mountain.

21 21 b Olympics showed numerous world record changes. US long jumper Bob Beacom, beat the existing world record by nearly two feet, at the 1968 Mexico City Olympic Games Bob Beamon Olympic Record Long Jump.wm

22 5. Scale a device used to measure weight. 22 d. Time - seconds - clock, duration required for a given number of vibrations of Cesium. Time Distortion - In 1975 Professor Carol Allie of the University of Maryland tested Einstein s theory using two synchronized atomic clocks. One clock was loaded on a plane and flown for several hours, while the other clock remained on the ground at the air base. Upon return, the clock on board the plane was found to be ever so slightly slower that the one on the ground. This was not due to experimental error, and has been repeated numerous times with the same result. Time travel

23 23 e. Charge - coulomb x the charge of an electron. 6. Derived Units and Tools a combination of measurements to describe 1 measurement a. Volume - amount of space occupied by an object. SI units of m 3 measures l x w x h 1. Liquid volume - liter - volumetric flask, graduated cylinder Dry volume - m 3 - meter stick

24 b. Temperature - degrees - thermometer, measure of Kinetic Energy Celsius - AKA Centigrade - based on freezing and melting points of water. a. Freezing = 0 Cº Boiling = 100 Cº b. Kelvin - based on Absolute Zero - Temperature where all molecular motion ceases. c. 0 K = Cº 273 K = 0 Cº 373 K = 100 Cº

25 d. Fahrenheit devised by using an unmarked thermometer and the following. 1. Middle mark was placed on the thermometer in freezing distilled water. 2. Lowest mark was placed on the thermometer in freezing, saturated, salt water The top level mark was made by placing the thermometer under your arm pit. If the bottom mark was labeled as 0 degrees and the upper level was labeled as 100 or 98.6 then the middle level was roughly 1/3 the distance, thus Density (p)- a ratio of mass /volume - g/cm 3 Show a density column

26 3. Area - measures surface area of an object l x w Ampere - SI measure of electric current

27 5. Candela - SI unit of light intensity Joule - SI unit of heat, amount of energy needed to raise 1 g of H 2 O 1 degree Cº a. Heat -Energy that moves from a higher source to a lower one. Measured with a Calorimeter.

28 b. Specific Heat Capacity - Energy needed to change the temperature of a substance. Which will heat up the slowest. 28

29 c. Calorie - 1 calorie = 4.18 J Mole SI unit for the amount of matter. E. Mathematical Relationships /sigfig5.htm 1. Factor Label Method - used to convert derivedd units.

30 a. Convert 8 ft/sec to miles/hr 8 ft 3600 sec 1 mile 1 sec 1 hour 5280 ft b. Remember to create a conversion box to use this method. c. Work some Problems on Homework Sheet. 2. Relative Error - uncertainty in a measurement, or device precision / measurement accuracy. 30 a. A measurement of 12.7 cm using, a meter stick with 1 mm increments. b. Remember to keep values the same, thus 1 mm is changed to.1 cm or visa versa, c..1 cm/12.7 cm = 8 x Ratio - relationship between 2 numbers.

31 31 4. Equations - uses number to perform the following describes a property, concept, or how quantities change together. 5. Symbol α means proportional to, like your weight is proportional to your position. F. Metric Conversions 1. Giga --Mega -- Kilo Hecto Deka BASE deci centi milli -- micro -- nano pico Work some Examples off the worksheet for Convert the Following G. Significant Digits - Number of digits that can be used for an answer. 1. The following are Significant a. All whole numbers

32 b. All zero s between whole numbers c. All zero s after a WHOLE NUMBER when decimal point is present 2. These are not significant a. Zeros after whole number without a decimal point b. Zeros before whole numbers H. Scientific Notation - exponent to express large or small # s Most correct when there is 1 digit to the left of the decimal point. 2. In addition or subtraction use least # of places after the decimal point. Example 1 Example no places after decimal point = 1 x or 1.23 x In multiplication or division use least # of significant digits. Example 1 Example 2

33 111 all have 3 sig. Dig. 5 x 5 = 2 x x = 1.37 x 10 3 I. Simple Line Graph 1. Linear Relationship Shows a straight line. 2. Direct Variation Shows an increase of both variables. 3. Independent Variable - AKA manipulated variable - the variable that is changed by the experimenter, it is plotted on the x axis Dependent Variable - AKA responding variable The variable that changes due to the change in the other variable, the observed change is plotted on the y axis. J. Inverse Relationship - one variable is dependent on the inverse of the other. K. Quadratic Relationship - parabolic curve type in which one variable is dependent on the square of the other variable.

34 L. Slope expressed as the change of y over the change of x. 34