Dr. Gerhard G. PaulusAssociate ProfessorDepartment of Physicshttp://faculty.physics.tamu.edu/ggp/email: [email protected] use “physics 218” in subject lineWhat is Physics ?Science of observing, measuring and understanding (calculating, predicting) phenomena in nature.Physics is the science of measuring and calculating physical quantities.In short: At the end, you want to have a physical quantity as a result of your measurement/calculation.Why physics ?ancient world and agriculture• surveying and mapping• astronomy• irrigation and water supplyrenaissance:• navigation• medicineindustrialization:• basis of the other natural sciences• basis for all kinds of engineering last not least:• physics is a great cultural achievement of mankind• physics teaches you thinking analytically mathematicsphysicsengineeringWhy physics ?Learning at university and in professional careersuccess depends primarily on you !!!and to a much smaller extend on your professor or TAsuccess does NOT depend much on what was before college!mathematicsphysicsengineeringSTEPS: the integrated approachmathematicsphysicsengineeringThere is lab this week!Physical QuantitiesPhysics is the science of measuring and calculating physical quantities.In short, at the end of a calculation, we want to have a physical quantity at the left side of the “=” - sign.Examples:masslengthtimeareavelocityenergyforcetemperaturevolumeBut: How to we communicate or write down physical quantities?UnitsPhysical quantities are expressed in multiples of units.Example: the mass of the steak I’ve ordered is 0.5 pounds.Units are not physics, they are legal issues!See: labels of the calibration authorities at filling stations broadcasted time However, physicists help the lawmakers. By order of the lawmaker they (i.e. NIST in the US) establish, conserve, and distribute units. Doing so, they meet essential needs of high-tech industry and technology.See: cell phones, global positioning system (GPS), semiconductor industry.PrefixSymbolFactorExampleTeraT1012Modern laser produce peak powers of several TeraWattGigaG109Nowadays computer have clockrates of 2 GHz and moreMegaM106A modest power plant delivers a power of 100 MWkilok103The distance to Houston is 130 km---100decid10-1One Liter equals 1 dm3centic10-2A piece of paper (US letter) is 27.9 cm highmillim10-3microµ10-6structures on a modern chip are 0.35µm widenanon10-9picop10-12femtof10-15the shortest laser pulses have a duration of 5 fsThe Basic Units of the Système International (SI)physical quantityunitsymboltimesecondsmasskilogramkglengthmetermThe British System1760 3 124840 9 144gallonquartpintcupfl. ouncetable spoontee spoon4 2 2 8 2 3tonpoundouncedram2000 16 16length: 1 inch = 25.4mmarea:volume: 1 gallon = 231 inches3mass: 1 pound = 0.4535... kgmile yard feet inchacre yard2 feet2 inch2Derived Unitsarea1 m2square metervolume1 m3cubic metervelocity1 m/smeter per secondacceleration1 m/s2meter per square secondforce1 kg m/s2 =: 1 NNewtonenergy1 kg m2/s2 =: 1 JJouleBe friendly to units !Remember: Physical quantities are numbers multiplied with a unit. This is what you want to have at the left hand side of the “=”-sign finally.This means: Treat units as algebraic quantities!Don’t add different unit!Example: 3.5m + 1.5m = 5m ok! 7kg + 500g = 7.5 kg wonderful! 3.5m + 5kg = no sense!Applications:- Conversion of units- Dimensional analysisReminder of TrigonometryReminder of TrigonometryScalar and and vectorial quantitiesarea1 m2square metervolume1 m3cubic metervelocity1 m/smeter per secondacceleration1 m/s2meter per square secondforce1 kg m/s2 =: 1 NNewtonenergy1 kg m2/s2 =: 1 JJouleVectors & EquilibriumF2F1F3xy63.43°4.47 N2.83 N4.47 N45.00°26.57°Name: ! ! ! ! ! ! ! ! ! Section:(no credit if not written clearly!)! ! ! ! ! ! (no credit if wrong!)Quiz 011. Convert meters to millimeters:1.4 m = mm2. Convert miles per hour to meters per second: (1 mile = 1609 m, 1 h = 3600s)50 mph = m/sCalculusGottfried Wilhelm Leibniz (1646-1716)Sir Isaac Newton (1643-1727)x1x2f(x1) f(x2) x2− x1f(x2) − f(x1)f(x2)−f(x1)x2−x11 1.1 1 1.21 0.1 0.21 2.11 1.01 1 1.0201 0.01 0.0201 2.011 1.001 1 1.002001 0.001 0.002001 2 .0011 1.0001 1 1.00020001 0.0001 0.00020001 2.0001x1x2f(x1) f(x2) x2− x1f(x2) − f(x1)f(x2)−f(x1)x2−x12 2.1 4 4.41 0.1 0.41 4.12 2.01 4 4.0401 0.01 0.0401 4.012 2.001 4 4.004001 0.001 0.004001 4 .0012 2.0001 4 4.00040001 0.0001 0.00040001 4.0001x1x2f(x1) f(x2) x2− x1f(x2) − f(x1)f(x2)−f(x1)x2−x13 3.1 9 9.61 0.1 0.61 6.13 3.01 9 9.0601 0.01 0.0601 6.013 3.001 9 9.006001 0.001 0.006001 6 .0013 3.0001 9 9.00060001 0.0001 0.00060001 6.0001Name Lab Sectio n No.(no credit if illegible) (no credit if wrong)Quiz 2a) Calculatelimx2→x1f(x2) − f (x1)x2− x1for f(x) = kx2.b)
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