Monday, February 16, 2015

Chapter 8 Notes

8.1 FORCE

-This table below shows the five common derived units in the SI system.

(Picture was saved from Alexandra's blog)

-Force=mass*acceleration
-F=ma
- The acceleration of something depends on the force exerted on it and its mass.
- SI unit of force=newton
- A newton is defined as the force required to accelerate a mass of one kilogram at a rate of one meter per second squared.
- A pound can be used as a unit of mass or force.

8.2 WEIGHT

- The difference between weight and mass:
-Mass is a measure of how much matter an object has. Weight is a measure of how strongly gravity pulls on that matter. For example, astronauts have the same mass in space, but a different weight because of weaker gravity.

8.3 DENSITY

- Density is the mass of an object divided by the volume the object occupies.
- Density is shown as p
-p=m/V
- Specific gravity (SG) of an object is a dimensionless ratio of the density of the object to the density of water.
            -SG= Density of object/Density of water
- Specific gravity limits
 - Solids> .5, <23
 - Liquids ~1
- Glasses ~0.001-0.0001
 -*exceptions:
              -iodine, 4.93
              -mercury, 13.6

8.4 AMOUNT

-Difference in amount in grams and the amount in moles:
            -grams=mass
            -moles=units of something
-If we have 12 of something it’s a dozen. If we have 20 of something it’s a score. If we have 6.022 X 10^23 it’s a mole.
 -Avogadro’s Number:
            -Avogadro’s Number= 6.022 X 10^23 mol^-1
            -It is difficult to measure a substance in moles, but it is easy to measure its mass.
            -Avogadro’s number offers a conversion path between moles and mass.

8.5 TEMPERATURE

-Four temperature scales:
            -Celsius
            -Fahrenheit
            -Kelvin
            -Rankine

T [Fahrenheit] – 32 / 180= T [Celsius] – 0 / 100
T [Kelvin] = T [Celsius] + 273
T [Rankine] = T [Fahrenheit] + 460

-The Kelvin and Rankine scales are absolute, which means that at absolute zero, the temperature at which molecules have minimum possible motion, the temperature is zero.

8.6 PRESSURE

-Pressure is defined as force acting over an area, where the force is perpendicular to the area.
-A pascal is the unit of pressure.
-One newton of force acting on an area of one square meter.
Pressure = force / area
Pa = N / m^2
-Atmospheric pressure: pressure created by the weight of air above us.
            -Standard atmospheric pressure is an average air pressure at sea level
            -Defined as one atmosphere [atm]
            -~14.7 pound-force per square inch. [psi]
-Absolute pressure = Gauge pressure + Atmospheric pressure
-Hydrostatic pressure: pressure exerted on a submerged object by the fluid in which it is immersed.
-Total pressure: the combination of atmospheric and hydrostatic pressure.
-Gas pressure: pressure created by a gas inside a closed container.

8.7 GAS PRESSURE:

- Ideal Gas Law
            PV = nRT
            -Only Kelvin or Rankine can be used in the ideal gas equation
            -P: Pressure
            -V: Volume
            -n: Amount s of gas in closed container
            -R: Gas constant

            -T: Temperature (either in Kelvin or Rankine)



No comments:

Post a Comment