GP1 Lesson #1_Units_Physical Quantities.pptx

measurement and physical quantities

1. June 10, 2019 GENERAL PHYSICS 1

2. Units & Physical Quantities *Measurement of the world

3. Physical Quantities and Units Physical Quantity any number that is used to describe a physical phenomenon quantitatively STANdard a reference for a unified measurement referred by everyone

4. International System of Units QUANTITY UNIT SYMBOL Length meter m Mass kilogram kg Time second s Electric current ampere a Temperature kelvin K Amount of substance mole mol Luminous Intensity candela cd

5. International System of Units LENGTH meter One meter is the distance travelled by light in vacuum during a time interval of 1/299792458 of a second. 1971: 1/10,000,000 of the distance from the equator to the North Pole 1989: distance between 2 engraved lines on a platinum bar 1960:wavelength of orange light (Kr)=1,650,763.73 wavelenght

6. International System of Units TIME time One second is the duration of 9192631770 periods of the radiation corresponding to the transition between two hyperfine levels of the ground state of cesium-133 atoms. Previously: 1/86,400 of a mean solar day

7. International System of Units MASS mass One kilogram is the mass of the standard platinum – iridium cylinder kept at the International Bureau of Weights and Measures in France.

8. International System of Units TEMPERATURE One kelvin is the fraction 1/273.16 of the triple point of water. Electric current One ampere is the constant current flowing in each of two long parallel wires, 1.0 m apart, that would produce between these wires a force equal to 2 x 10^-7 newton per meter of length of each wire.

9. International System of Units Luminous Intensity One candela is the luminous intensity in a given direction of a source that emits a monochromatic radiation of frequency 540 x 10^12 Hz and that has a radiant intensity in that direction of 1/683 watts per steradian. Amount of substance One mole is the amount of substance that contains as many atoms or molecules as there are atoms in 0.012 kg of carbon-12.

10. International System of Units General conference on weights and measures November 2014 (25 th meeting) = revision the cesium hyperfine splitting frequency 9192631770 hertz for second; the speed of light in vacuum of 299792458 meters per second; the luminous efficacy Kcd of monochromatic radiation of frequency 540 x 10^12 hertz is exactly 683 lumens per watt for the candela; the Plank’s constant is h equal to 6.62606 x 10^-34 joule-second for kilogram;

11. International System of Units General conference on weights and measures the elementary charge e equal to 1.60217 x 10-19 coulombs for the ampere; the Boltzmann constant kB equal to 1.3806 x 10^-23 joules per kelvin for the kelvin; and the Avogadro’s constant NA equal to 6.02214 x 10^23 mol^-1 for the mole.

12. Unit Prefixes Length across scales.

13. Why Learn to Measure? Valuable skill for a job Valuable skill for hobbies Valuable skill for every day life

14. unit a standard amount of a dimensional quantity (e.g. meter) Physical Quantities and Units British system of units customary Metric system Syst ẻme International SI units

15. Standard (Customary) System Inches Fractions 2 4 8 16 ¼ ¾ The Whole Inch First Half Second Half 1 / 8 3 / 8 5 / 8 7 / 8 1 / 16 3 / 16 5 / 16 7 / 16 9 / 16 11 / 16 13 / 16 15 / 16

16. 1. Find out how many parts the inches are divided into. Count the spaces in 1 inch. This number will be the denominator. 2. Count the number of whole inches. Write down the number. 3. Count the number of spaces after the last whole inch. This number will be the numerator. 4. Reduce fraction, if necessary. Steps in Using the Standard (Customary) System

17. Step 1 Step 2 Step 3 Find Denominator Count Whole Inches Find Numerator Step 4 Reduce Fraction, If Necessary Let’s Review 16 7 1

18. Let’s Practice! What is the distance from the end of the ruler to A? What is the distance from the end of the ruler to E? What is the distance from the end of the ruler to D? What is the distance from the end of the ruler to C? What is the distance from the end of the ruler to B? ¼ in. 15/16 in. 1 ¾ in. 2 3/8 in. 3 1/16 in.

19. Metric System International System of Units (SI) Millimeters and Centimeters Decimals 1 mm = 0.1 cm 5 mm = 0.5 cm 10 mm = 1 cm

20. Steps in Using the Metric (SI) System Count the number of whole centimeters (cm). These are the larger lines with numbers 2. Count the number of lines after the whole number. The smaller lines are millimeters (mm). 3. Put in correct terms. Since mm are 1/10th of a cm, if you measure 7 marks after 1 cm, the measure is 1.7 cm or 17 mm long.

21. Let’s Practice! What is the distance from the end of the ruler to A? What is the distance from the end of the ruler to E? What is the distance from the end of the ruler to D? What is the distance from the end of the ruler to C? What is the distance from the end of the ruler to B? 4 mm = 0.4 cm 19 mm = 1.9 cm 37 mm = 3.7cm 63 mm = 6.3cm 73 mm = 7.3cm

22. Converting from Standard to Metric Convert from: To: Multiply by: mile kilometer (km) 1.609347 inch millimeter (mm) 25.4 inch centimeter (cm) 2.54 foot meter (m) 0.3048 yard meter (m) 0.9144

23. Converting from Metric to Standard Convert from: To: Multiply by: kilometer (km) mile 0.6214 millimeter (mm) inch 0.0394 centimeter (cm) inch 0.3937 meter (m) foot 3.281 meter (m) yard 1.094

24. Let’s Practice! You used a meter stick to measure your window for new shades. However, the shade packages list the measurements in English units. Luckily your cell phone has a calculator so that you can quickly convert your 81.3 cm by 91.4 cm window opening to English units. What size is your window using English units? Round to the nearest inch. 81.3 x .3937 = 32 in. 91.4 x .3937 = 36 in. Therefore, the window opening is 32 in. by 36 in.

25. Conversion of Units British System of Units a standard of measurement used in US and few other countries LENGTH: 1 inch = 2.54 cm FORCE: 1 pound = 4.448221615260 newtons 1. How many inches are there in 3 meters? 2. How many newtons of force do you need to lift 34 pound bag?

26. ROUnding off numbers Rules: Know which last digit to keep. This last digit remains the same if the next digit is less than 5. Increase the last digit if the next digit is 5 or more. A rich farmer has 87 goats – round it to nearest 10. Round off to the nearest tenths: 3.1416 8.345

27. Activity A tractor-trailer truck is traveling at 60 miles per hour eastbound on Interstate 195 towards the North Dartmouth exit. Determine the speed of the truck In feet per second In meters per second In kilometers per hour

28. “What Happens If We Mix Units?”

29. Direction: In a quarter sheet of paper, answer the following items. Which of the following nation create the SI? America C. Greece France D. Italy 2. If centi is 10-2 , then micro is 10 -3 C.10 -5 10 -4 D. 10 -6 3. Which among these SI is for luminous intensity? Ampere C. kelvin Candela D. mole 4. What is the basis for a kilogram? Krypton atom C. Platinum-Iridium alloy Cesium atom D. None of the above 5. Which of the following is in British system of units? Ampere C. newton Centimeter D. pound