Question

Bryan Allen pedaled a human-powered aircraft across the English channel from the cliffs of Dover to Cap Gris-Nez on June 12, 1979. He flew for 169 minutes at an average velocity of 3.53 m/s in a direction 45.0∘ degrees south of east. Allen encountered a headwind averaging 2.00 m/s almost precisely in the opposite direction of his motion relative to the earth. What was his average velocity relative to the air?

Answer 1

Answer:

The answer is "$5.53 \ \frac{m}{s}$"

Explanation:

apply the formula for calculating the average velocity to the relative air

$V_{PG} =V_{PA}+V_{AG}$

$\Rightarrow V_{PA} = V_{PG} -V_{AG}$

Given value:

$V_{AG} = -2 \ \frac{m}{s}$

$V_{PG} =3.53$

$\Rightarrow V_{PA} = 3.53 - (-2) \\\\\Rightarrow V_{PA} = 3.53 +2 \\\\\Rightarrow V_{PA} = 5.53$

The final answer is "$5.53 \ \frac{m}{s}$" in the south-east direction.