Sep. 22 In-class Optional Assignment Answers
If you completed and turned in the assignment in class
you will earn 0.2 extra credit points.
1a. Does air pressure INCREASE
DECREASE
or remain CONSTANT with increasing altitude?
1b. Does air density INCREASE DECREASE or
remain CONSTANT with increasing altitude?
Both air
pressure and air density decrease with increasing altitude.
Pressure at any level in the atmosphere is determined by the weight of
the air overhead. There is less and less air above as you move
upward in the atmosphere, so pressure decreases. An air layer at
some level in the atmosphere is compressed by the weight or pressure of
the air above. Since pressure decreases with increasing altitude,
the layers of air are compressed less and the air
density decreases.
2. How many feet are in 1 mile?
There are 5280
feet in a mile (5000 feet per mile is probably close enough in this
class). A "nautical" mile has 6076 feet and is thus slightly
longer than a "statute" mile. 1 knot is 1 nautical mile per hour
and is slightly faster than 1 MPH. Most of the time in this class
we will assume that knots and MPH are equivalent.
3. Archimedes Law tells us that an object
immersed in water will experience an upward bouyant force equal to the
water of the water displaced. Archimedes Law
allows you to determine the strength of the upward buoyant force but
doesn't tell you what causes it. What does cause the upward bouyant
force?
Pressure
increases as you go deeper and deeper in the water (it increases very
quickly because water is much denser than in air). The pressure
of the water pushing upward on the bottom of can of soda (a) is greater
than the pressure of the water pushing down on the top of the can
(b). The pressures pushing sideways (c) are all of equal strength
and cancel out. This results in a net upward pressure difference
force.
4.
a. winds from
the NE at 5 knots
b. winds from
the SW at 15 knots
c. winds from
the NW at 20 knots
d. winds from
the NE at 1 to 2 knots
5. What time is it in Greenwich England when it is 2:00 pm
in Tucson?
Greenwich
England is 7 hours later than Mountain Standard Time. Thus it is
9:00 pm in Greenwich.
Ordinarily 2:00
pm would be converted to the 24 hour format. 2:00 pm =
14:00. To convert to Greenwhich Mean Time, Universal Time, or
Zulu time you would need to add 7 hours.
2:00 pm MST =
21:00 Z
