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# Chapter 1 measurements

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### Chapter 1 measurements

1. 1.  System of Units  Fundamental Quantities  Derived Quantities  Units  Prefixes  Conversion of Units  Significant Figure
2. 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. 3. SYSTEM OF UNITS  Basic Quantities  Derived Quantities  Units  Prefixes
4. 4. Physical Quantities * Basis of physical quantities * Combination of one or more basic quantity quantities BASIC QUANTITIES DERIVED QUANTITIES •Basis of physical quantities •Example : Length (m) Mass (kg) Time (s) Temperature (K) Electric current (A) •Combination of one or more basic quantities. •Example : Area (m2) Volume (m3) Velocity (ms-1) Acceleration (ms-2)
5. 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. 6.  Other quantities which defined in term of seven (7) fundamental quantities.  Example:  Speed  Work  Force  Electric Potential  Power  Frequency  Angle 6 6 Derived Quantities
7. 7. BASIC QUANTITIES COMBINATION OF QUANTITIES DERIVED QUANTITIES Length (Length)2 Area(m2) Length (Length)3 Volume(m3) 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 length)/(time)2 Force(kgms-2)
8. 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 called the International System or SI based on the metric system. UNITS 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. 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. 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. PREFIXES
11. 11.  2000 m = 2 x 103 m = 2 km  0.005 m = 5 x 10-3 m = 5 mm  45 000 000 bytes = 45 x 106 bytes = 45 Mbytes  0.00000008 s = 80 x 10-9 s = 80 ns  200 mA = 200 x 10-3 A PREFIXES Example :
12. 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. 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. 14.  45 cm = ? km km4.5x10cm45 km45x10cm45 m1000 1km cm100 1m xcm45cm45 4 5 CONVERSION OF UNITS
15. 15.  35 km.hr-1 = ? m.s-1 11 ms9.72km.hr35 s m 60x60 35x1000 1hr km35 s60 1min min60 1hr km1 m1000 1hr km35 hr1 km35 CONVERSION OF UNITS
16. 16.  20 kg.m-3 = ? g.cm-3 323 33 3 3 33 3 33 cm.g10x2m.kg20 cm g 100x100x100 1000x20 m1 kg20 cm100 m1 kg1 g1000 m1 kg20 m1 kg20 cm100 m1 kg1 g1000 m1 kg20 m1 kg20 CONVERSION OF UNITS
17. 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 0.000999 121000  Numbers having two significant figures: 16 8.9 0.12 0.0082 17 17 Significant Figures
18. 18. 1. Non zero integers always count as significant figures. 2. Zeros: There are three classes of zeros. • Leading zeros • Captive zeros • Trailing zeros 18 18 Rules for Significant Figures
19. 19. a) Leading zeros  Zeros that precede all the non zeros digit  They do not count as significant figures  Ex: 0.000562 [3 s.f] b) Captive zeros  Zeros between non zeros digits. They always count as significant figures  Ex: 13.009 [5 s.f.] c) 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. 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. 21. Adding or Subtracting • Ex: 12.11 + 8.0 + 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. 22. 1. 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. 2. If the resultant force on an object of mass 260 kg is 5.20 x 102 N, use equation F = ma to find acceleration. 3. 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. 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. 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 23 23 2 2 2 260 1020.5 / ms x mFa mssmtvl 7105.35/20 Due to the least s.f. (72x103m/h = 2 s.f.), thus the answer is 0.71 km or 7.1x102m. Solutions
24. 24. ~Setiap yang berusaha pasti akan BERJAYA~ Thank You…