Question

In 5 hours a small plane can travel downwind for 4000 kilometers

or upward 3000 kilometers. Find the speed of this plane with no wind and the speed of the wind current.

write as an equation​

Answer 1

the speed of the plane with no wind is 700 km/h and the speed of the wind is 100 km/h

Explanation:

Let V be the speed of the plane and v the speed of the wind. Down current, they are in opposite directions, and the plane travels a a distance of 4000 km in 5 hours,so

5(V - v) = 4000

V - v = 800 (1)

For upwind movement, since the plane travels 3000 km in 5 hours, so

5(V + v) = 3000

V + v = 600 (2)

adding equations (1) and (2), we have

V - v = 800

+

V + v = 600

2V = 1400

V = 1400/2 = 700 km/h

subtracting equations (2) from (1), we have

V - v = 800

-

V + v = 600

-2v = 200

v = -200/2 = -100 km/h

So, the speed of the plane with no wind is 700 km/h and the speed of the wind is 100 km/h