Physics Notes

June 23

Technical Measurements and Vectors

*experiments to test hypotheses, and to make accurate an accurate analysis you need measurements.

*Physical quantity
- measured by comparison with some known standards
- defined by telling how it is named
- ex: "seconds" is a unit of time, light-years is a unit of distance.
Magnitude: written as (Value then unit) 32kg - thirty two kilograms.

*IS/SA/Metric System/Systeme International d'unites
-Derived units for common physical quantities
Tera - T - 1,000,000,000,000
Giga - G - 1,000,000,000
Mega - M - 1,000,000
Kilo - k - 1,000
Centi - c - 0.01
Mili - m - 0.001
Micro - μ - 0.000001
Nano - n - 0.000,000,001
----(angstrom) - Å - 0.000,000,000,1
pico - P - 0.000,000,000,001


Radian - angle at the apex of a slice of pie whose straight and curved edges all have the same length (r).

*Significant Figures
-Rules:
0s between nonzero figures are significant. (606)
0s in front of nonzero numbers are insignificant. (06)
0s at the end of a number and to the right of a decimal point are significant (.6000)

*When working with formulas...
1.) If two quantities are to be added or subtracted, they must be the same
dimensions. (i.e. you cannot add amperes and meters, but you can add meters and feet.)
2.)the quantities on both sides of the equation must be the same dimensions
(i.e. light-years cannot be equal, to, say, kilograms!)

*Newton's laws of motion
1. First Law: Every body will persist in its state of rest or of uniform motion (constant velocity) in a straight line unless it is compelled to change that state by forces impressed on it. This means that in the absence of a non-zero net force, the center of mass of a body either is at rest or moves at a constant velocity.
2. Second Law: A body of mass m subject to a force F undergoes an acceleration a that has the same direction as the force and a magnitude that is directly proportional to the force and inversely proportional to the mass, i.e., F = ma. Alternatively, the total force applied on a body is equal to the time derivative of linear momentum of the body.
3. Third Law: The mutual forces of action and reaction between two bodies are equal, opposite and collinear. This means that whenever a first body exerts a force F on a second body, the second body exerts a force −F on the first body. F and −F are equal in magnitude and opposite in direction. This law is sometimes referred to as the action-reaction law, with F called the "action" and −F the "reaction".



Typing the notes is too much of a hassle now (I'm Lance, hello) so I'm going to stop trying. This isn't as fun as typing chem notes. I'm sure the people that really -do- want to learn physics actually pay attention and take down notes, but, for the people that have trouble even then, please refer to Patrick's resource here. It renders notes obsolete anyway. If enough people somehow want me to put up notes again I'll see what I can do.



Meter:
/Original (old) standard/
1/10,000,000 of the distance
from the north pole to the
equator (1960)
or 1,650,763.73 wavelengths
of orange-red light from krypton 86

/Current (new) standard/
Distance traveled by light
in a vacuum in a time interval
of (3.3x10 to the negative 9th times
s to the negative one) or 199,
792,48s