DX 17. The hourly temperature at Portland, Oregon, on a particular day is recorded below. 1 AM
46°
1 P. M.
720
2
449
2
749
3
43°
3
750
4
41°
4
5
40°
5
77°
6
40°
6
75°
7
41°
7
749
8 9
43° 46°
8 9
70° 62°
10
52°
10
55°
11
65°
11
51°
12 Noon
699
12 Midnight
48°
75°
a. Find the amplitude of a sinusoidal function that models this temperature variation.
b. Find the vertical shift of a sinusoidal function that models this temperature variation.
c. What is the period of a sinusoidal function that models this temperature variation?
d. Use t=0 at 5 P. M. to write a sinusoidal function that models this temp. variation.
e. What is the model's temperature at 10 A. M? Compare this to the actual value?

The consumption of fossil fuels could be

Aball tossed vertically upward from the ground next to a building passes the bottom of a window 1.8 s after being tossed and passes the top of the window 0.20 s later. the window is 2.0 m high from top to bottom. what was the ball's initial velocity? the unit vector j^ is directed upward. how far is the bottom of the window from the launch position? how high does the ball rise above the launch position?

As part of an industrial process, air as an ideal gas at 10 bar, 400k expands at steady state through a valve to a pressure of 4 bar. the mass flow rate of air is 0.5 kg/s. the air then passes through a heat exchanger where it is cooled to a temperature of 295k with negligible change in pressure. the valve can be modeled as a throttling process, and kinetic and potential energy effects can be neglected. (a) for a control volume enclosing the valve and heat exchanger and enough of the local surroundings that the heat transfer occurs at the ambient temperature of 295 k, determine the rate of entropy production, in kw/k. (b) if the expansion valve were replaced by an adiabatic turbine operating isentropically, what would be the entropy production? compare the results of parts (a) and (b) and discuss.