Chapter 8, Problem 30RE

Finding the speed of a Glider From a glider 200 feet above the ground, two sightings of a stationary object directly in front are taken 1 minute apart (see the figure). What is the speed of the glinder?

To determine

To find: What is the speed of the glider?

Answer to Problem 30RE

Hence the speed is $132.55\text{ ft/min}$.

Explanation of Solution

Given:

From a glider 200 feet above the ground, two sightings of a stationary object directly in front are taken 1 minute apart (see the figure).

Formula used:

$\text{tanθ }=\text{ opp}/\text{adj}$

Calculation:

Let $x$ be the distance the boat is from the shore.

$\tan 10°=\frac{y}{200}$

$y=200\text{tan}10°$

$y=35.27\text{ ft}$

$\tan 40°=\frac{200}{x+y}$

$x+y=\frac{200}{\tan 40°}$

$x+y=238.35\text{ ft}$

$x=167.82-35.27\text{ ft}$

$x=132.55\text{ ft}$

The glider travels $132.55\text{ ft}$ in 1 min.

Hence the speed is $132.55\text{ ft/min}$.