Newton's Laws of Motion

Newton's first law of motion, also called the law on inertia, states that an object continues in its state of rest or of uniform motion unless compelled to change that state by an external force.

Newton's second law of motion states that if a net force acts on an object, it will cause an acceleration of that object.

Newton's third law of motion states that for every action there is an equal and opposite reaction.
Kepler's Laws of Planetary Motion

The law of orbits: All planets move in elliptical orbits with the sun at one focus.

The law of areas: A line joining a planet and the sun sweeps out equal areas in equal time.

The law of periods: The square of the period (T) of any planet is proportional to the cube of the semimajor axis (r) of its orbit, or T^{ 2}=(4π^{2}/GM) r^{3}, where M is the mass of the planet.
Einstein Postulates of Special Relativity
 The laws of physics are the same in all inertial reference frames.
 The speed of light is the same regardless of the frame of reference of the observer.
Other Principles and Laws
Pascal's principle: The pressure applied at one point in an enclosed fluid under equilibrium conditions is transmitted equally to all parts of the fluid.
Archimedes' principle: The magnitude of a buoyant force on a completely or partially submerged object always equals the weight of the fluid displaced by the object.
International System of Units
Quantity 
SI Unit 
American Unit 
Conversion (if applicable) 
Length 
Meter (m) 
Foot (ft) 
1 m = 3.281 ft 
Time 
Second (s) 
Second (s) 
n/a 
Mass 
Kilogram (kg) 
Pound (lb) 
1 kg =2.205 lb 
Electric current 
Ampere (A) 
Ampere (A) 
n/a 
Amount 
Mole (mole) 
Mole (mole) 
n/a 
Temperature 
Celsius (°C)
or Kelvin (K) 
Fahrenheit (°F) 
°C = ^{5}⁄_{9}(°F  32°) 
Common Formulas
Name 
Abbrev. 
Formula 
Speed of light 
c 
3.0 ×10^{8} m/s 
Gravitational constant 
G 
6.67 × 10^{11} Nm^{2}/kg^{2}

Electron and proton charge 
e 
1.6 × 10^{19} C 
Boltzmann's constant 
k 
1.38 × 10^{23} J/K 
Gas constant 
R 
8.31 J / mole K 
Permittivity of free space 
_{o} 
8.85 × 10^{12} C^{2} / Nm 
Permeability constant 
µ_{o}

1.26 × 10^{6} T m / A 
Avagadro's number 
N 
6.02 × 10^{23}

Electron mass 
m_{e}

9.11 × 10^{31} kg 
Planck's constant 
h 
6.63 × 10^{34} J s 
Values
Prefix 
Abbrev. 
Value 
nano 
n 
10^{9}

micro 
µ 
10^{6}

milli 
m 
10^{3}

centi 
c 
10^{2}

kilo 
k 
10^{3}

mega 
M 
10^{6}
