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)
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