An airplane flies at 100km/h in still air. if it flies into a 10 km/h headwind, its groundspeed is

a) 100 km/h
b) 110 km/h
c) 120 km/h
d) 90 km/h

D)

Explanation:

The groundspeed of the airplane is equal to the speed of the airplane in still air, plus the speed of the air. Since the plane flies with headwind, the sign of the air speed is negative, since it is contrary to the movement of the airplane.

Now, we have:

Here is the airplane groundspeed, the airplane speed and the air speed

magnitude and direction

graph slopes whilst gas cools, then it is flat whilst conensation to liquid happens, the coolong liquid then graphs as a slope when it solidifies graph is flat

latent heat