Scientific measurements

• Measurement- assignment of a numerical value to an objects physical property
• Units- standardized amounts of physical quantities to express and compare measurements (i.e, size, magnitude)
• Base Units- fundamental; for base quantities (chosen by convention)
• Derived Units- calculated using algebraic combinations of base units
• Cgs- the abbreviation for the centimeter-gram-seconds (system of units)
• fps- feet, pound, seconds "stroud system" invented by william stroud (english)
• Mksa- meter, kilogram, seconds and ampere
• Si- system international [meter (length), Kelvin (temp.), seconds (time), kg (mass), mol (amount of substance), ampere (electric current), candela (luminous intensity)
• Metric System: units are categorized by factors of 10

  uses prefixes
• mega (10^6) kilo (10^3) hecto (10^2) deca (10^1)

  
  

  micro (10^-6) milli (10^-3) centi (10^-2) deci (10^-1)
• Non- Si units (chem) ||| angstrom (A)- length atom size= 1/10 nm ||| tonne/ metric ton (t)- 1000kg (commercial unit volume) atmosphere (atm) - P (air P at sea level) liter (L)- volume- 1d^3
• area- m^2, volume m^3, velocity m/s, acceleration- m/s^2, density kg/m^3
• force- N = kg•ms > 1dym= 10^-3 || pressure- Pa = N/m^-2 > 1atm = 1.013x10^5 Pa || energy- J= N•m> 1cal= 4. 184 J || power- W = J/s || electric charge- C= A•S
• unit conversion- the process of converting a quantity from one unit to another, by factors of 10, 1st 3 prefixes above or below the base unit (x/10), beyond x/1000 ( ex. nm> mm [si] base unit m)
• Length: 1 in= 2.54 cm, 1mi= 1.609 km mass: 1 lb= 453.6 g
• significant figures- known digit + 1 estimated digit device limited measurements 0.560 vs 560. vs 560