## 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 semi-major 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} |