+956 An airplane is heading north with an airspeed of 400 km/h. The plane encounters a wind from the east at 100 km/h. What is the magnitude of the resultant ground velocity?
a) 387 km/h
b) 400 km/h
c) 412 km/h
d) 500 km/h
So this got me a bit confused: I did:
√[ (400)^2+(100)^2 ] = 412 km/h
HOWEVER
√[ (400)^2-(100)^2 ] = 387 km/h
Which one is correct? I think it's C though
+129899 Let the airplane be represented by the vector < 0, 400 >
Let the wind be represented by the vector < -100, 0 >
The components of the airplane vector are 400 cos 90 = 0 and 400 sin 90 = 400
The components of the wind vector are -100 cos 180 = 100 and -100 sin180 = 0
So....the resultant vector is found as
sqrt [ ( 0 + 100 )^2 + ( 400 + 0 )^2 ] =
sqrt [ 10000 + 160000 ] =
sqrt [ 170000] =
412.3 km / h = 412 km/h [rounded ]
