Editing Variometer (section)

===Total energy compensation in theory===
[[File:Variometer4.png|thumb|300px|metric variometer on a towed glider]]
The total energy of the aircraft is:

1.  <math>E_\text{tot} = E_\text{pot} + E_\text{kin}</math>

where <math>E_\text{pot}</math> is the potential energy, and <math>E_\text{kin}</math> is the kinetic energy. So the change in total energy is:

2.  <math>\Delta E_\text{tot} = \Delta E_\text{pot} + \Delta E_\text{kin}</math>

Since

3.  Potential energy is proportional to height

<math>E_\text{pot} = m g h</math>

where <math>m</math> is the glider mass and <math>g</math> the acceleration of gravity

and

4.  Kinetic energy is proportional to velocity squared,

<math>E_\text{kin} = {1 \over 2} m V^2</math>

then from 2:

5.  <math>\Delta E_\text{tot} = m g \Delta h + {1 \over 2} m {\Delta V}^2</math>

6. Typically, this is converted to an effective altitude change by dividing by the acceleration of gravity, and the mass of the aircraft, so:

<math>{\Delta E_\text{tot} \over m g}= \Delta h + {{\Delta V}^2 \over 2g}</math>