Prefix: K, Kilo- = 1000 = 103.
Three laws of motion by Sir Isaac Newton (1687). The 1st law: An object will remain at constant velocity unless a non-zero force acts upon it. The 2nd law: The force will accelerate an object in the direction of that force; the acceleration is proportional to the force and inversely proportional to the object’s mass. The 3rd law: For every force, there is an equal and opposite force.
Three thermodynamics laws. The 1st law: Energy cannot be created or destroyed, but only converted from one form to another. The 2nd law: Heat cannot of itself pass from a colder to a warmer body. The 3rd law: The entropy of ordered solids reaches zero at the absolute zero of temperature.
Three Kepler’s laws on planets’ orbital movement around the Sun. The 1st law: Each planet’s orbit is an ellipse with the Sun at one focus. The 2nd law: The rate of area that swept by a planet along its orbit is constant. The 3rd law: The ratio of the semi-major axis to the square of the period is constant for all the planets.
The well-known “three-body problem” in mathematical physics, studied by many mathematicians D’Alembert, Leonhard Euler, Joseph-Louis Lagrange, Jacobi and Laplace…
3-dimensional (3D or 3-D) figure has length, width and height/depth (or 3 coordinates).
The number of means of heat transfer: heat connection, heat conduction and heat convection.
The number of different classifications of rock: igneous, metamorphic (or pyroclastic) and sedimentary.
The triple point of water is the thermodynamic temperature at which water forms an interface of 3 phases: solid, liquid and vapor: 0.01 oC (Celsius or centigrade) = 273.16 K (Kelvin) = 32.018 oF (Fahrenheit).
Frequency Ranges
|
Range |
Names |
Uses |
|
3 Hz – 300 Hz |
Extremely Low Frequency (ELF) |
Telegraph |
|
300 Hz – 3 KHz |
Voice Frequency (VF) |
Telephone Circuitry |
|
3 KHz – 30 KHz |
Very Low Frequency (VLF) |
High Fidelity |
|
30 KHz- 300 KHz |
Low Frequency (LF) |
Maritime Mobile |
|
300 KHz – 3 MHz |
Medium Frequency (MF) |
Navigational Radio, Land-maritime Mobile |
|
3 MHz – 30 MHz |
High Frequency (HF) |
Maritime, Aeronautical, Amateur Radio |
|
30 MHz – 300 MHz |
Very High Frequency (VHF) |
Maritime, Meteorological Communication, Television |
|
300MHz – 3 GHz |
Ultra High Frequency (UHF) |
Television, Military, Low Range Radar |
|
3 GHz – 30 GHz |
Super High Frequency (SHF) |
Space, Satellite, Microwave |
|
30 GHz – 300 GHz |
Extremely High Frequency (EHF) |
Radio Astronomy |
