1994 Paper 3 Q10

Year: 1994
Paper: 3
Question Number: 10

Course: LFM Pure and Mechanics
Section: Vectors

Difficulty: 1700.0 Banger: 1502.0

Problem

The island of Gammaland is totally flat and subject to a constant wind of \(w\) kh\(^{-1},\) blowing from the West. Its southernmost shore stretches almost indefinitely, due east and west, from the coastal city of Alphabet. A novice pilot is making her first solo flight from Alphaport to the town of Betaville which lies north-east of Alphaport. Her instructor has given her the correct heading to reach Betaville, flying at the plane's recommended airspeed of \(v\) kh\(^{-1},\) where \(v>w.\) On reaching Betaport the pilot returns with the opposite heading to that of the outward flight and, so featureless is Gammaland, that she only realises her error as she crosses the coast with Alphaport nowhere in sight. Assuming that she then turns West along the coast, and that her outward flight took \(t\) hours, show that her return flight takes \[ \left(\frac{v+w}{v-w}\right)t\ \text{hours.} \] If Betaville is \(d\) kilometres from Alphaport, show that, with the correct heading, the return flight should have taken \[ t+\frac{\sqrt{2}wd}{v^{2}-w^{2}}\ \text{hours.} \]

No solution available for this problem.

Rating Information

Difficulty Rating: 1700.0

Difficulty Comparisons: 0

Banger Rating: 1502.0

Banger Comparisons: 2

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Problem source
The island of Gammaland is totally flat and subject to a constant
wind of $w$ kh$^{-1},$ blowing from the West. Its southernmost shore
stretches almost indefinitely, due east and west, from the coastal
city of Alphabet. A novice pilot is making her first solo flight from
Alphaport to the town of Betaville which lies north-east of Alphaport.
Her instructor has given her the correct heading to reach Betaville,
flying at the plane's recommended airspeed of $v$ kh$^{-1},$ where
$v>w.$ 

On reaching Betaport the pilot returns with the opposite heading to
that of the outward flight and, so featureless is Gammaland, that
she only realises her error as she crosses the coast with Alphaport
nowhere in sight. Assuming that she then turns West along the coast,
and that her outward flight took $t$ hours, show that her return
flight takes 
\[
\left(\frac{v+w}{v-w}\right)t\ \text{hours.}
\]
If Betaville is $d$ kilometres from Alphaport, show that, with the
correct heading, the return flight should have taken 
\[
t+\frac{\sqrt{2}wd}{v^{2}-w^{2}}\ \text{hours.}
\]