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The distance from Parrot Point Airport to the Ivy Cliffs is 291 miles at and angle of 9.1 degrees northeast. There is a wind blowing southeast at 25 miles per hour. You want to make this trip in 3 hours by flying straight there. At what speed* and heading should you fly?

User Baijum
by
7.3k points

1 Answer

3 votes

Answer:

The speed V = 194.03 mph

Direction = 3.6° northeast

Explanation:

The distance of the trip = 291 miles

The direction of flight = 9.1 degrees northeast

Speed of the prevailing wind = 25 mph

Direction of wing = southeast = 45 degrees South of East

The speed heading to Ivy Cliffs = V₁

V×(sin(9.1) + cos(9.1)) + 25×(-sin(45) + cos(45)) × t₁ = 291 miles

V×(sin(9.1) + cos(9.1)) + 25×(sin(45) + -cos(45)) × t₂ = 291 miles

t₁ + t₂ = 3 hours

(V×(sin(9.1)-25×(sin(45))j + (V×cos(9.1) + 25×cos(45))i

The magnitude V² = V²+29.32·V +625= 291²/t₁²......(1)

Also on the return trip we have;

V²-29.32·V +625= 291²/(3-t₁)²..........................................(2)

Subtracting equation (2) from (1) gives;

58.64·V = 291²/t₁² - 291²/(3-t₁)² = 291²×(6·t-9)/(t²·(t-3)²)

V = 291²×(6·t-9)/(t²·(t-3)²)/58.64

Substituting the value of V in (2) with a graphing calculator gives;

t₁= 1.612 or 1.387

Given that magnitude of the speed going > return = V² for t₁ < t₂

t₁ = 1.387, t₂ = 1.612

From V²+29.32·V +625= 291²/t₁², we have

V²+29.32·V +625= 291²/1.387²

Which gives

V²+29.32·V -43336.5 = 0

(V + 233.35)(V-194.03) = 0

V = -233.35 mph or V = 194.03 mph

Given that V is a natural number, we have, V = 194.03 mph.

The direction is given by the relation;

V×(sin(9.1) + cos(9.1)) + 25×(-sin(45) + cos(45)) × t₁ = 291 miles

V×(sin(9.1) + cos(9.1)) + 25×(-sin(45) + cos(45)) × t₁ = 291 miles

194.03×sin(9.1 degrees)-25×sin(45 degrees)j + 194.03×cos(9.1 degrees) + 25×cos(45 degrees)i = 291/1.387

13j + 209.27i = 208.81 mph

The angle tan θ = 13/209 = 0.00622

θ = tan⁻¹(13/209.27) = 3.6°.

User Suganya Selvarajan
by
6.4k points
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