Brooke E.

Physics

the study of energy and its interactions with matter

Length

meter- based on the speed of light

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mass

kilogram- mass of a particular platinum alloy cylinder

time

second- based on the frequency of electromagnetic waves emitted by Cesium 133

temperature

Kelvin- same size as a Celsius degree

electric current

ampere- one coulomb of charge per second

luminous intensity

candela- produces 1/683 watts per steradian

Mole

unit of quantity; 6.02x10^23 particles, hot dogs, etc.

Derived units

composed of base units.

ex: m/s^2 or 1 Newton= 1 Kgm/s^2

10^6

mega

10^3

kilo

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10^2

hecto

10^1

deca

10^-1

deci

10^-2

centi

10^-3

milli

10^-6

micro

to convert from one unit to another,

replace the original unit with its equivalent amount of the new unit

ex: 3kg = 3(1000g)= 3000g

Dimensional analysis

the process of dividing out, combining and expanding units to check the validity of equations and substitutions

Trigonometry

the use of solutions of triangles to solve problems

Trig for a right triangle

sin: O/H

cos: A/H

tan: O/A

h^2= ha^2 + ho^2

law of cosines

(not right triangle)

c^2= a^2+ b^2

-2abcosC

Law of Sines (not right triangle)

sinA/a = sinB/b=

sinC/c

A, B, C stand for

the angles of the triangle

a, b, c

represent sides opposite of corresponding angles

scalar quantity

has magnitude but no direction

ex: mass

vector quantity

both magnitude and direction

ex: weight

Direction of arrow

is the direction of the vector

length of arrow

is the magnitude of the vector

when 2 vectors are added

both size and direction of each vector must be taken into account when finding the resultant.

if the vectors are in the same direction,

add them numerically and assign their direction of the resultant

if the vectors are in opposite directions,

subtract the smaller from the larger and assign the direction of the larger to the resultant.

if the vectors are placed head to tail,

they all form an angle other than 0 or 180 degrees, draw a diagram and use trig functions to solve the resulting triangle for the magnitude of the resultant and direction

when vectors form a right triangle,

the pythagorean theorem can be used to find the magnitude of the resultant. Then use the inverse tangent to find the direction.

when vectors do not form a right angle,

the law of cosines is used to find the magnitude of the resultant and the law of sines is used to find the directions.

Vector subtraction

is done the same way except the vector being subtracted is drawn in the direction opposite to its original direction

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