If it were not for the greenhouse effect on Earth,
a. there would be no liquid water on Earth.
b. life as we know it would not have developed on Earth.
c. it would be a much colder planet.
d. there would be no oxygen in Earth's atmosphere.
e. All of the above are results of the greenhouse effect.
e. All of the above are results of the greenhouse effect.
You might also like to view...
Tripling the frequency of a photon would ______________ its energy
Fill in the blank(s) with correct word
How do we know that different colors of light have different speeds in a material?
a. Because of measurements by Galileo of the speed of different colors of light. b. Because different colors reflect at different angles. c. Because the index of refraction depends on the speed of light in a material, and that index is different for different colors. d. Because Fizeau's measurements measured different colors of light to have different speeds. e. Because the colors combine to form white light.
Hot water is to be heated from 10 to 30°C, at the rate of 300 kg/s by atmospheric pressure steam in a single-pass shell-and-tube heat exchanger consisting of 1-in. schedule 40 steel pipe. The surface coefficient on the steam side is estimated to be 11,350 W/(m2 K). An available pump can deliver the desired quantity of water provided the pressure drop through the pipes does not exceed 15 psi. Calculate the number of tubes in parallel and the length of each tube necessary to operate the heat exchanger with the available pump.
GIVEN
Single-pass shell-and-tube heat exchanger Water is heated by atmosphere steam Water temperatures
? Tw,in = 10°C
? Tw,out = 30°C Water flow rate ( m w)= 300 kg/s Inner tube: 1 in. schedule 40 steel pipe Maximum water pressure drop (?p) = 15 psi = 103,422 N/m2 Steam side heat transfer coefficient ( oh ) = 11,350 W/(m2 K)
FIND
(a) The number of tubes in parallel (N)
(b) The length of each tube (L)
ASSUMPTIONS The tube is smooth The tube is 1% carbon steel Uniform pipe surface temperature Fully developed flow in pipe Water flow is turbulent to insure good heat transfer
SKETCH
PROPERTIES AND CONSTANTS
for 1 in. schedule 40 pipe
Inside diameter (Di) = 1.049 in. = 0.0266 m
Outside diameter (Do) = 1.315 in. = 0.0334 m
the saturation temperature of steam at 1 atm = 100°C
for water at the average temperature of 20°C
Absolute viscosity (?) = 993 × 10–6 Ns/m2
Density (?) = 998.2 kg/m3 Specific heat (cpw) = 4182 J/(kg K)
Thermal conductivity (kw) = 0.597 W/(m K)
Prandtl number (Pr) = 7.0,
the thermal conductivity of 1% carbon steel (ks) = 43 W/(m K).
Answer the following statement(s) true (T) or false (F)
1. The sun’s mass is about 1000 times that of Jupiter, and the radius of Jupiter’s orbit is about 1100 times the sun’s radius. The center of mass of the sun/Jupiter system is inside the sun. 2. Two stars, one with radius r and the other with radius 3r, orbit each other so that their centers of mass are 25r apart. Assume that the stars have the same uniform density. This system’s center of mass is inside the larger star. 3. Kepler’s 2nd law applies to hyperbolic orbits. 4. Kepler’s 3rd law applies to hyperbolic orbits.