F3 SI Units and Measurement PDF

 Learning Objectives 2  To correctly use significant figures  To identify the SI units  To convert measurement units using prefixes  A. SI units 3 How long does it take to…. …walk from home to school? minutes Time …hop...

 Learning Objectives 2  To correctly use significant figures  To identify the SI units  To convert measurement units using prefixes  A. SI units 3 How long does it take to…. …walk from home to school? minutes Time …hop to the door? seconds …sleep through the night? hours …fly around the world? days  A. SI units 4 How would we measure mass in … …Cyprus? kilograms Mass …UK? stone …Canada? pounds … Physics? kilograms  A. SI units u n c e s 5 o Farenheit s s m n r e i llo t il fe ga pin le s ya et t rds inches Celsius  A. SI units 6 The Hubble telescope cost $36 million, but it did not work! The telescope was built using metric units, but the mirrors using imperial units, so the mirror did not fit. NASA did not find out the problem until the first fuzzy pictures were sent back from Space.  A. SI units 7 Fixing the problem International System of Units; Made in 1960 from the ‘metric system’; Uses the base 10; Used in science and commerce more than other measurement systems like ‘imperial’.  A. SI units 8 SI Base Unit Base Quantity Name 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  A. Question 9 SI Base Unit Base Quantity Name Symbol length meter m mass kilogram kg time seconds s electric current ampere A temperature Kelvin K amount of substance moles mol luminous intensity candela cd  A. Question 10 kilogram second international units Kelvin meter International system of ___________ The Standard ______________ units are the standard base units used by people around the second world. These include ______________ for time, Kelvin ______________ kilogram for temperature, ______________ for meter mass and ______________ for length.  A. SI units Derived units 11 What is the derived unit of FORCE? What is the SI unit of FORCE? F = ma N k g m/s 2  A. Question 12 newton N joules J watt pascal C V ohms  B. Measurements 13 Standard prefixes allow units to be modified so as to deal more easily with very small and very large quantities. i.e. length of 1000 m is exactly the same as length of 1 km.  B. Measurements 14 Factor Name Symbol 109 (1 000 000 000) giga G 106 (1 000 000) mega M 103(1 000) kilo k 10-2 (1 / 100) centi c 10-3 (1 / 1 000) milli m 10-6 (1 / 1 000 000) micro μ 10-9 (1 / 1 000 000 000) nano n  B. Question 15 1. ms = millisecond 2. MJ = _______________ megajoule 3. nm = _______________ nanometer 4. kW = _______________ kilowatt 5. μm = _______________ micrometer 6. cm = _______________ centimeter 7. GV = _______________ gigavolt 8. mA = _______________ milliamp 9. MPa = _______________ megapascal 10. kilonewton kN = _______________  B. Measurements Example: length 16 ÷ 1 000 000 (×10-6) ÷ 1000 (×10-3) ÷ 1000 ÷ 10 ÷ 100 (×10-2) × 1000 (×103) μm mm cm m km × 1000 × 10 × 100 ( 10-2) ÷ 1000 ( 103) × 1000 ( 10-3) × 1 000 000 (10-6)  B. Measurements 17 The easiest way to convert from a unit Factor Name Symbol with a prefix to one without a prefix is to replace the prefix with the factor it 109 giga G stands for: 106 mega M o 5 km = 5 ×10 = 5 000 m 3 103 kilo k 10-2 centi c o 5 Mm = 5 ×10 = 5 000 000 m 6 10-3 milli m o 5 mm = 5 ×10 = 0.005 m-3 10-6 micro μ o 5 μm = 5 ×10-6 = 0.000005 m 10-9 nano n  B. Measurements 18 The easiest way to convert from a Factor Name Symbol unit without a prefix to one with a prefix is to divide by the factor it 109 giga G stands for: 106 mega M o 5000 m = 5000 10 = 5 km 3 103 kilo k 10-2 centi c o 5 000 000 m = 5 000000  10 = 5 Mm6 o 0.005 m = 0.005  10 = 5 mm -3 10-3 milli m o 0.000005 m = 0.000005  10-6 = 5 μm 10-6 micro μ 10-9 nano n  B. Question 19 1. 0.45 km = 0.45 x 103 m = 450 m 2. 300 x 10-2 = 3 300 cm = _______________________________________ m 3. 5 MW = ________________________________________ 5 x 106 = 5 000 000 W 4. 525 x 103 = 525 000 525 kg = _______________________________________ g 5. 9 x 109 = 9 000 000 000 9 GJ = _________________________________________ J  B. Question 20 6. 250 mA = ______________________________________ 250 x 10-3 = 0.25 A 7. 0.5 x 103 = 500 0.5 kN = _______________________________________ N 8. 750 μm = ______________________________________ 750 x 10-6 = 0.00075 m 9. 50 x 103 = 50 000 50 kJ = ________________________________________ J 10. 15 mg = _______________________________________ 15 x 10-3 = 0.015 g  B. Question 21 11. 5.5 x 10 3 = 5500 5.5 km = ________________________________________ m 12. 50 x 106 = 50 000 000 50 MPa = _______________________________________ Pa 13. 8000 m = _______________________________________ 8000 ÷ 10-3 = 8 km 14. 50 ÷ 10-3 = 0.515 515 g = ________________________________________ kg 15. 95 000 000 N = ___________________________________ 95 000 000 ÷ 10-6 = 95 MN 16. 15 x 10-2 x 10-2 = 8 80 000 cm2 = _____________________________________ m2  B. Question 22 17. 3000 x 10-3 = 3 3000 mm = ________________________________________ m 18. 0.230 x 103 = 230 0.230 kV = ________________________________________ V 19. 5300000 ÷ 10-6 =5.3 5 300 000 J = ______________________________________ MJ 20. 2 ÷ 10-2 = 200 2 m = ____________________________________________ cm 21. 15 ÷ 10-3 = 0.015 15 g = ____________________________________________ kg 22. = 0.08 m3 80 000 cm3 = _______________________________________ 80000 x 10-2 x 10-2 x 10-2  B. Question 23 SI unit of time 3000 m 3 kg = __________ s symbol for second m a unit of time 3000 g symbol of milli kilogram SI unit of length Mm symbol of kilogram kg 3 km = __________ pounds a unit of mass second SI unit of mass meter symbol for megameters minute  B. Question 24 If a snail 🐌 travels 80 mm in 60 s. What is its speed? Give your answer in different appropriate units. speed = distance/time speed = 80/60 = 1.3 mm/s or speed = 8/60 = 0.13 cm/s or Speed = 0.08/1 = 0.08 m/min  B. Question 25 What is the area of a rectangle measuring 5 cm by 20 mm? Give your answer in 2 different units. (Remember that units must be consistent throughout the same question). For square units (e.g. area) you use A = l x w = 5 x 2.0 = 10 cm 2 the conversion twice! or For cubic units (e.g. volume) you use A = l x w = 50 x 20 = 1000 mm2 the conversion three times!  C. Significant figures 26 Unlike Maths, you will not be given the number of significant figures (sig figs) your answer should be in. You can work it out from the data you used to work out the answer (and don’t forget of course to round up if necessary). The general rule is: The final answer cannot have more sig figs than the least number of sig figs you used in the calculation!  C. Question 27 Alex measures a rectangle to be 12.6 cm tall and 5.8 cm wide. She calculates the area of the rectangle as follows: 12.6 cm × 5.8 cm = 73.08 cm2 Write down the answer to the correct number of sig figs and explain your reasoning? 73 cm2 (2sf) because the least number of sig figs used is 5.8 which is 2sf  C. Question 28 Charlie uses electronic timers to measure the speed of a cyclist. The cyclist travels 35.00 m in 3.67 s. She calculates the cyclist's speed as follows: 35.00 m ÷ 3.67 s = 9.536784741 m/s Write down the answer to the correct number of sig figs and explain your reasoning? 9.54 m/s (3sf) because the least number of sig digs used is 3.67 which is 3sf