For nearby spirals, their rotation curves help measure both light and dark matter
Indicate whether the statement is true or false
TRUE
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According to current estimates, rice agriculture will expand by up to 70% over the next 25 years to support the growing human population. This will not be any sort of massive problem for Earth's ecosystem to bear
What will be an ideal response?
A circumferential fin of rectangular cross section, 3.7-cm-OD and 0.3-cm-thick surrounds a 2.5- cm-diameter tube as shown below. The fin is constructed of mild steel. Air blowing over the fin produces a heat transfer coefficient of 28.4 W/(m2 K). If the temperatures of the base of the fin and the air are 260°C and 38°C, respectively, calculate the heat transfer rate from the fin.
GIVEN
FIND
ASSUMPTIONS
The system has reached steady state
The mild steel is 1% carbon steel
The thermal conductivity of the steel is uniform
Radial conduction only (temperature is uniform across the cross section of the fin)
The heat transfer from the end of the fin can be accounted for by increasing the length by half the
thickness and assuming the end is insulated
SKETCH
PROPERTIES AND CONSTANTS
Thermal conductivity of 1% carbon steel (k) = 43 W/(m K) at 20°C
The energy of nuclear radiation as it is absorbed mostly goes to heat the material
a. True b. False Indicate whether the statement is true or false
A gamma ray is another name for a(n)
a. electron. b. proton. c. neutron. d. helium nucleus. e. photon.