Question

a motor boat is traveling at 25 knots towards 340 degree on a river flowing at 20 knots towards 175 degrees. What is the actual speed of the boat as seen by a helicopter piolet hovering above?

Answer 1

Answer:

Vbx = 25 * cos 340 = 23.5 knot        x-component of boats speed

Vrx = 20 cos 175 = -19.9 knot        x-component of rivers speed

Vx = 3.58 knot      x-component of boat and river speed

Vby = 25 sin 340 = -8.55 knot    y-component of boat speed

Vry = 20 sin 175 = 1.74 knot    y-component of river speed

Vy = -6.81 knot     y-component of boat and river speed

V = (Vx^2 + Vb^2)^1/2 = (3.58^2 + 6.81^2)^1/2 = 7.69 knots