Answer:
The speed of the submarine is 15.429 miles per hour.
Step-by-step explanation:
Let suppose that both ships travel at constant velocities. As we know that both travel in opposite directions, it is supposed that cruise ship moves in +x direction, whereas submarine in -x direction. Kinematic equations for each sheep are described below:
Ship
Submarine
Where:
- Position of Diego Garcia island, measured in miles.
, 
- Current positions of ship and submarine, measured in miles.
, 
- Velocities of ship and submarine, measured in miles per hour.
- TIme, measured in hours.
If we know that 
, 
and 
, then:
We clear now the velocity of submarine:
Speed of the submarine is the magnitude of its velocity, which is 15.429 miles per hour.
Answer:
Non-repeating decimal
Step-by-step explanation:
As a example, 32.93729, would be a never ending number. Which means it's not a rational number, it is a irrational number.
The total area of the complete lawn is (100-ft x 200-ft) = 20,000 ft².
One half of the lawn is 10,000 ft². That's the limit that the first man
must be careful not to exceed, lest he blindly mow a couple of blades
more than his partner does, and become the laughing stock of the whole
company when the word gets around. 10,000 ft² ... no mas !
When you think about it ... massage it and roll it around in your
mind's eye, and then soon give up and make yourself a sketch ...
you realize that if he starts along the length of the field, then with
a 2-ft cut, the lengths of the strips he cuts will line up like this:
First lap:
(200 - 0) = 200
(100 - 2) = 98
(200 - 2) = 198
(100 - 4) = 96
Second lap:
(200 - 4) = 196
(100 - 6) = 94
(200 - 6) = 194
(100 - 8) = 92
Third lap:
(200 - 8) = 192
(100 - 10) = 90
(200 - 10) = 190
(100 - 12) = 88
These are the lengths of each strip. They're 2-ft wide, so the area
of each one is (2 x the length).
I expected to be able to see a pattern developing, but my brain cells
are too fatigued and I don't see it. So I'll just keep going for another
lap, then add up all the areas and see how close he is:
Fourth lap:
(200 - 12) = 188
(100 - 14) = 86
(200 - 14) = 186
(100 - 16) = 84
So far, after four laps around the yard, the 16 lengths add up to
2,272-ft, for a total area of 4,544-ft². If I kept this up, I'd need to do
at least four more laps ... probably more, because they're getting smaller
all the time, so each lap contributes less area than the last one did.
Hey ! Maybe that's the key to the approximate pattern !
Each lap around the yard mows a 2-ft strip along the length ... twice ...
and a 2-ft strip along the width ... twice. (Approximately.) So the area
that gets mowed around each lap is (2-ft) x (the perimeter of the rectangle),
(approximately), and then the NEXT lap is a rectangle with 4-ft less length
and 4-ft less width.
So now we have rectangles measuring
(200 x 100), (196 x 96), (192 x 92), (188 x 88), (184 x 84) ... etc.
and the areas of their rectangular strips are
1200-ft², 1168-ft², 1136-ft², 1104-ft², 1072-ft² ... etc.
==> I see that the areas are decreasing by 32-ft² each lap.
So the next few laps are
1040-ft², 1008-ft², 976-ft², 944-ft², 912-ft² ... etc.
How much area do we have now:
After 9 laps, Area = 9,648-ft²
After 10 laps, Area = 10,560-ft².
And there you are ... Somewhere during the 10th lap, he'll need to
stop and call the company surveyor, to come out, measure up, walk
in front of the mower, and put down a yellow chalk-line exactly where
the total becomes 10,000-ft².
There must still be an easier way to do it. For now, however, I'll leave it
there, and go with my answer of: During the 10th lap.
