Algodoo

Looks good and works the way you would expect. The math may not be correct (see Heat Transfer Lumped Analysis), but that might not matter. In short, the braking energy would go directly into the rotor while at the same time the rotor would be exponentially cooling at a rate depending on the temperature difference between the rotor and the surrounding air.

P.S. For more accurate modeling:

Initialize variables:

_tempAir := 20.0;
_tempOld := _tempAir;
_capacity = 0.1;
_resistance = 20.0;


colorHSVA := {
[20, 1, 1, (_temp - _tempAir) / 100.0]
};

In postStep:

Keys.isDown(_key) ? {
_heat = Scene.my.abs(_torque * angvel)
} : {
_heat = 0
};
_temp = _tempOld + _heat / (_capacity * Sim.frequency) + (_tempAir - _temp) / (_capacity * _resistance * Sim.frequency);
_tempOld = _temp;

Note: The cooling time constant = _resistance * _capacity

If you want to plot temperature:

colorHSVA := {
[20, 1, 1, (_temp - _tempAir) / 100.0];
scene.my.angVel = (_temp - _tempAir) / 100.0;
};

In a circle with center hinge put "angVel = scene.my.angVel", then plot the angular velocity for that circle.

- This is SIMPLE only visual braking effect, that have ONLY 2 lines of code (see older scene, this newer one is for kids, because older version can be powered only by engine, or another coaxial hinge,and can be also used as handbrake if you toggle input), no variabiles etc.
- My old code in Dragster was similar to yours (except _tempAir), but command "clamp" help me to heavily reduce script
- Ok, i can add it later in another scene (_temp-_tempAir)ˇ2
and air temperature can be zero, because there almost no diference
(unless you are driving in hell where temperature is +-500°C )

Regarding "ONLY 2 lines of code", I'm proposing 3 lines. I know it's 50% more code, but that's the price you pay for more accurate results (linear heating with exponential cooling).

I recently updated Braking Bad. I liked your tight coding so much that I used your code with the modifications mentioned above.