chapter1measurements-130713122315-phpapp01 (1)[1].pptx

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1. System of Units Fundamental Quantities  Derived Q uantities Units Prefixes Conversion of Units Significant Figure

2. State the definition and differences of based and derived quantities. able to list down the SI Prefixes. know how to apply the significant figures make a conversion of any units given by using simple & common method of rational number method

3. SYSTEM OF UNITS Basic Quantities Derived Quantities Units Prefixes

4. Physical Quanti t ies BASIC QU A NTITI E S DERIVED QU A NTITI E S Basis of physical quantities Example :  * L B e a n s g is th of (m ph ) ysical M qu a a s n s t ( it k ie g s ) Time (s) Temperature (K) Electric current (A) Combination of one or more basic quantities. Example : A * re C a o ( m m b 2 i ) nation of V o o n l e um or e m ( o m re 3 ) basic V q e u l a o n c t i i t t y y ( q m ua s n -1 ti ) ties Acceleration (ms -2 )

5. Also known as Base Quantities 5 5 Fundamental Quantities Quantity Unit Abbreviation Length (l) meter m Time (t) second s Mass (m) kilogram kg Electric Current (I) ampere A Temperature (T) kelvin K Amount of Substance Mole mol Luminous Intensity candela cd Table 1: SI Base Quantity and Units

6. Other quantities which defined in term of seven (7) fundamental quantities. Ex a m ple: Speed W ork Force Electric Potential Power Frequency Angle 6 6 Derived Quantities

7. BASIC QUANTITIES COMBINATION OF QUANTITIES DERIVED QUANTITIES Length (Length) 2 Area(m 2 ) Length (Length) 3 Volume(m 3 ) Length, time Length/time Speed(ms -1 ) Length, time Length/(time) 2 Acceleration(ms -2 ) Length, mass Mass/(length) 3 Density(kgm -3 ) Mass, time (Mass x l e ngth) / ( t ime ) 2 Force(kgms -2 )

8. Physical quantities measured by using unit. Example: Length is a physical quantity. 1960 – General Conference on Weights and Measures decided on a universal system of unit cal l ed the International System or SI based on the metric system. U N I T S Physical Quantity Unit of Measurements Symbol Length Metre m Mass Kilogram kg Time Second s Electric current Ampere A Thermodynamic temperature Kelvin K Amount of substance Mole mol Luminous intensity Candela cd

9. A way of writing numbers that accommodates values too large or small to be conveniently written in standard decimal notation. In scientific notation, numbers are written in the form: Example: An electron's mass is about 0.000 000 000 000 000 000 000 000 000 000 910 938 22 kg. In scientific notation, this is written 9.1093822 10 −31 kg.

10. Used to simplify big numbers. Replace powers of ten. To make the calculation easier. Y, Z, E, h, da, a, z, and y are rarely used. PR E F I X E S

11. PR E F I X E S Example : 2000 m = 2 x 10 3 m = 2 km 0.005 m = 5 x 10 -3 m = 5 mm 45 000 000 bytes = 45 x 10 6 bytes = 45 Mbytes 0.00000008 s = 80 x 10 -9 s = 80 ns 200 mA = 200 x 10 -3 A

12. Any quantity can be measured in several different units. Hence it is important to know how to convert from one unit to another. Multiplying or dividing an equation by a factor of 1 does not alter an equation. Example: Length: foot / inch / metre 12 12 CONVERSION OF UNITS

13. 3 km = ? m 1 km = 1000 m 3 km = 3 x 1000 m =3000 m OR 3 km = 3 km x 1000 m 1 km = 3000 m Conversion of Units

14. 45 cm = ? km 45 cm 45 cm 1m 1km 100 cm 1000 m 45 cm x 45 cm 45x10 5 km 4.5x10 4 km CONVERSION OF UNITS

15. 35 km.hr -1 = ? m.s -1 1 60 x 6 0 s 9.72 ms 1 35 x 100 0 m 1hr 35 km.hr 1h r 1 m i n 1km 60 min 60 s 1000 m 1 h r 1hr 35 km 35 km 35 km CONVERSION OF UNITS

16. 20 kg.m -3 = ? g.cm -3 3 3 2x10 2 g.cm cm 3 3 100x100x100 1m 3 20kg.m 100cm 3 g 1m 3 1m 3 1kg 20kg 20x1000 100cm 1m 3 1 m 1 g 1m 3 1kg 20kg 1000g 2 kg 1m 3 20kg 2 kg CONVERSION OF UNITS

17. The digits that carry meaning contributing to its precision. Retain all figures during calculation. The leftmost non-zero digit is sometimes called the most significant digit or the most significant figure . The rightmost digit of a decimal number is the least significant digit or least significant figure . Numbers having three significant figures: 587 0. 777 0.000 999 121 000 Numbers having two significant figures: 16 8.9 0. 12 0.00 82 17 17 Significant Figures

18. Non zero integers always count as significant figures. Zeros: There are three classes of zeros . Leading zeros Captive zeros Trailing zeros 18 18 Rules for Significant Figures

19. Leading zeros Zeros that precede all the non zeros digit They do not count as significant figures Ex: 0.000 562 [3 s.f] Captive zeros Zeros between non zeros digits. They always count as significant figures Ex: 13. 00 9 [5 s.f.] Trailing zeros Zeros at the end of numbers. They count as significant figures only if the number contains a decimal point. Ex: 200 [1 s.f.] 2.00 [3 s.f] 19 19 Rules for Significant Figures

20. Multiplying or Dividing Ex: 16.3 x 4.5 = 73.35 (but the final answer must have 2 s.f.) Therefore, 16.3 x 4.5 = 73 (2 s.f.) 20 20 Significant figure for final answer = the quantity which has the least number of significant figures Mathematical Operation For Significant Figures

21. Adding or Subtracting Ex: 12.11 + 8. + 1.013 = 31.123 The final answer is 31. 1 (1 decimal places) 21 21 Number of decimal places for final answer = the smallest number of decimal places of any quantity in the sum Mathematical Operation For Significant Figures

22. Ohms law states that V = IR. If V = 3.75 V and I = 0.45 A, calculate R and express your answer to the correct number of significant figures. If the resultant force on an object of mass 260 kg is 5.20 x 10 2 N, use equation F = ma to find acceleration. If a car is traveling at a constant speed 72 km/h for a time 35.5 s, how far has the car traveled? (use distance = speed x time ) 22 22 Exercise 1

23. 1. R = V/I = 3.75/0.45 = 8.3333333Ω Due to the least s.f. (0.45 = 2 s.f.), thus the answer is 8.3 Ω 2. 23 23 2 260 5.20 x 10 2 a F / m 2 ms Due to the least s.f. (260 = 2 s.f. ), thus the answer is 2.0ms- 2 3. Change v=72km/h to m/s => 72km/3600s=20m/s l v t 20 m / s 35.5 s 710 m Due to the least s.f. (72x10 3 m/h = 2 s.f.), thus the answer is 0.71 km or 7.1x10 2 m. Solutions

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