Ecor 1101 lec2

Ecor 1101 lec2 - 1 Lecture 01 General Principles...

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Unformatted text preview: 1 Lecture 01 General Principles Sec&ons 1.1 to 1.6 Pages 3 to 15 Prac&ce Problems 1.7, 1.9, 1.13, 1.15. 1.17 MES Assignment 01 2 Mechanics Solids Rigid Sta&cs: ECOR 1101, CIVE 2101 Dynamics: ECOR 1101, CIVE 2101, MAAE 2101 Deformable CIVE 2200, CIVE 3202 MAAE 2202, MAAE 3202 Fluids Compressible MAAE 2400 Incompressible MAAE 2300 3 Units 4 Conversion Factors Work problems in the units given unless otherwise instructed! 1 ft = 0.3048 m 1 lb = 4.4482 N 1 slug = 14.5938 kg 2.2 lb = 1 kg Example: Convert a torque value of 47 in lb into SI units. Answer is 5.31026116 N m? 5 SI Units No Plurals (e.g., m = 5 kg not kgs ) Separate Units with a (dot) (e.g., meter second = m s ) Most symbols are in lowercase. (Excep&ons: N, Pa, M and G) Exponen&al powers apply to units, e.g., cm cm = cm2 Compound prefixes should not be used. Other rules are given in your textbook. 6 Important You must use proper units in all your answers Marks will be deducted for failure to use the proper units. Most common mistakes kg is a unit of mass (not force) N is a unit of force (not mass) lb is a unit of force Slug is a unit of mass 7 Significant Figures Although you calculator is capable of handling and displaying 11 (or more) significant figures, engineering calcula&ons (answers) rarely require more than 3 or 4. Warning: Marks will be deducted for failure to use the appropriate number of significant figures in your submiCed work. 8 Idealiza&ons Par&cle Rigid Body Concentrated Force Newton's Laws Iner&a F = ma Ac&on - Reac&on 9 Newton's Laws Iner&a F = ma Ac&on Reac&on 10 Law of Gravita&on G = 66.73 "10 -12 m3 kg s2 m1m2 F = G 2 r Weight = Force of adrac&on between the Earth and an object of mass m " G ME % M Em F = G 2 =m$ 2 ' = mg # r & r ! W= mg 11 A 1 kg mass weighs 9.81 N A 1 slug mass weighs 32.2 lb 12 Calculations (Section 1.5) Must have dimensional "homogeneity." Dimensions have to be the same on both sides of the equal sign, (e.g. distance = speed time m = m/s x s) Use an appropriate number of significant figures (usually 3 for the answer, 4 for intermediate calcula&ons). Be consistent when rounding off. - greater than 5, round up (3528 3530) - smaller than 5, round down (0.03521 0.0352) - equal to 5 ?? 13 Prefixes MulDple 1 000 000 000 1 000 000 1 000 0.001 0.000 001 0.000 000 001 Exponent 109 106 103 10-3 10-6 10-9 Prefix giga mega kilo milli micro nano Symbol G M k m n 1 km = 1 000 m = 1 000 000 mm Working Problems Need paper, pencil, eraser, calculator, draiing equipment (ruler, compass, protractor) 15 16 17 ...
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This note was uploaded on 02/10/2012 for the course ECOR 1101 taught by Professor Ehabzalok during the Fall '10 term at Carleton CA.

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