The aircraft's own speed is 900 km / h, and the tailwind speed is 20 m / s. Determine the speed of the aircraft relative to the ground.

Hello,

In aeronautics there are two types of wind:  

These two speeds add up if the speed vector is in the same direction. The sum of these two winds is called apparent wind S(a)

The relative wind of the aircraft is in the opposite orientation of travel, whereas the true wind is in the orientations of motion. The velocity vectors are therefore in opposite directions, so the true wind speed must be subtracted from the relative wind. If we assume that the aircraft is in the perfect true wind direction, then :

S(a) = |S(r) - S(w)

The speed of the aircraft is therefore 828 km/h

.) the observation by semmelweis that more mothers died of childbed fever when their doctors also worked in the morgue

this is poiselle's equation from fluid mechanic in physics. mech eng