Chapter 8, Thinking Like an Engineer

1. The 5 most common dimensions and the SI Units and from where  they are derived (from the introduction paragraph)
   
   
   

   

   
   
   
   
2. Force
   F=ma
   The acceleration of an item depends on the force exerted on the item and the item's mass.
   SI force unit: Newton (named after Sir Isaac Newton)
   
   

   A Newton is "the force required to accelerate a mass of one kilogram at a rate of one meter per second squared."

   
   

   A Newton is a derived unit that combines mass, length, and time.

   The SI system is "coherent" because it is possible to combine base units.
3. Describe in your own words the difference between weight and mass
   
   
   Mass is a fundamental dimension that quantifies how much matter an object contains (constant). Weight is a force that equals the mass of an object multiplied by gravity (varies based on position in the universe).
   
   
4. Density
   Density = mass/ volume
   Common units for density: kg/m^3
   
   
5. Specific Gravity
   Dimensionless ratio:

   Specific Gravity= Density of object/Density of water

   Makes it possible for any unit system to be used in calculations 
   
   Specific gravity of liquids are around 1
   

     gases are between 0.001-0.0001

     densest substances a normal person encounters are around 21.5   

     (platinum) and 19.3 (gold)
   

   
   
6. Section 8.4 briefly discuss (1) Difference in amount in grams and the amount in moles and (2) Avogadro’s Number
   
   1) Amount in grams= mass
   Amount in moles=number of units of a substance
   
   

   Comparable to the meaning of a "dozen"

   
   

   A mole contains 6.022 x 10^23 units of something. 

   
   
   2) Avogadro's Number= 6.022 x 10^23
   This number originated from the following calculation: 

   1 atomic mass unit= mass of a nucleon = 1.66 x 10^24

   
   

   For every 1 atomic mass unit there are 1.66 x 10^24 grams of that substance

   
   

   1 amu/ 1.66 x10^24 grams = 6.022 x 10^23 amu/grams

   
   

   The numerical value, 6.022 x 10^23 was labeled as the fundamental unit, mole.

   
   

   A mole is 6.022 x 10^23 units of  something.

   
   
   Avogadro's number provides a conversion factor between mass and moles of a substance.
   
   
   
7. Four temperature scales
   Celcius (named for Anders Celsius)
   Fahrenheit (Gabriel Fahrenheit)
   Kelvin (First Baron William Thomson Kelvin)
   Rankine (William J.M. Rankine)
   
   Temperature[degrees Fahrenheit] = (9/5) * Temperature[degrees Celsius] + 32
   Temperature[Kelvin] = Temperature[degrees C] + 273
   Temperature[degrees Rankine] = Temperature[degrees F] +460
   
   Both Kelvin and Rankine are absolute scales, which means at the temperature at which molecules have the minimum amount of motion possible (absolute zero) the scale records a temperature of zero.
   
   Conversion factors: 
   1 degree Celsius/ 1.8 degrees Fahrenheit
   
   

   This is because there are 100 units between the freezing point of water and the boiling point of water on the Celsius scale. However, there are 180 units between the freezing point of water and the boiling point of water on the Fahrenheit scale.

   
   

   There is one degree Celsius per 1.8 degrees Fahrenheit. 

   
   

   

   
   
   1 Kelvin/1 degree Celsius
   1 degree Rankine/1 degree Fahrenheit 
   
   
8. Pressure (the 4 forms of pressure on fluids) Section 8.6 and 9. Ideal Gas Law
   
   Pressure: force acting over an area
   SI Units of Pressure: Pascal (Pa) = N/m^2
   

   One Newton of force acting on an area of 1 square meter

   Unit Pascal is named after Blaise Pascal

   
   Pressures involving fluids:
   
   

   Atmospheric pressure- pressure exerted by weight of air above us

   Standard atmospheric pressure/average air pressure at sea level: 14.7 psi

   psi= pound-force per square inch 

   
   

   Reference points: 

   absolute pressure (perfect vacuum) 

   denoted with an "a" -- psia 

   gauge pressure (local atmospheric pressure)

   denoted with a "g" --psig 

   Blood pressure and tire pressure are examples of gauge pressure 

   
   

   Absolute pressure = Gauge pressure + Atmospheric pressure

   
   
   

   Hydrostatic pressure- pressure exerted by fluid on a submerged object

   
   

   Governed by Pascal's law:

   Hydrostatic pressure = liquid density * cross-sectional area of container 

   
   

   Total pressure- atmospheric pressure + hydrostatic pressure 

   Gas pressure- pressure exerted by gas in closed container 

   
   

   Ideal Gas Law: PV = nRT      all temperatures are recorded in Kelvin

   
   

   P= absolute pressure in Pascals

   V= volume in Liters

   n= number of moles of gas in closed container

   R= gas constant = 0.08206 (atm*L) / (mol*K)

   = 8314 (Pa*L) / (mol*K)

   T= absolute temperature in Kelvin  

   
   

   An ideal gas: one mole of a gas at a temp of 273 Kelvin and a pressure of 1 atm (atmosphere) occupies a volume of 22.4 liters 

   
   

   The Ideal Gas Law can be used to solve for any of the related units: pressure, volume, moles, and temperature. It just depends on the given situation.