How fast is an ion of deuterium moving, assuming rms speed, if it is in a plasma with a temperature of 190 × 10^6 K? (kB = 1.38 × 10^–23 J/K and mD = 2 × 1.66 × 10^–27 kg)
a. 1.54E+6 m/s
b. 1.54E+4 m/s
c. 2.37E+12 m/s
d. 8.89E+5 m/s
e. 2.80E+6 m/s
a
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In a manufacturing process, a fluid is transported through a cellar maintained at a temperature of 300 K. The fluid is contained in a pipe having an external diameter of 0.4 m and whose surface has an emissivity of 0.5. To reduce heat losses, the pipe is surrounded by a thin shielding pipe having an ID of 0.5 m and an emissivity of 0.3. The space between the two pipes is effectively evacuated to minimize heat losses and the inside pipe is at a temperature of 550 K. (a) Estimate the heat loss from the liquid per meter length, (b) If the fluid inside the pipe is an oil flowing at a velocity of 1 m/s, calculate the length of pipe for a temperature drop of 1 K.
GIVEN
- Fluid in concentric pipes, with the space between the pipes evacuated, running through a cellar space
- Cellar temperature (T?) = 300 K
- External diameter of inner pipe (D1) = 0.4 m
- Emissivity of outer pipe surface (?1) = 0.5
- Inside diameter of outer pipe (D2) = 0.5 m
- Emissivity of inner pipe (?2) = 0.3
- Inside pipe temperature (T1) = 550 K
FIND
(a) The heat loss from the liquid per meter length (q/L)
(b) The length of pipe for a temperature drop of 1 K if the fluid is oil flowing at a velocity (V) =1 m/s
ASSUMPTIONS
- Steady state
- Convection between the pipes is negligible
- The thermal resistance of the pipe walls is negligible
- The thickness of the outer pipe wall is negligible (Inside surface area = Outside surface area)
- Area of the cellar is large compared to the pipe so that cellar behaves as a blackbody enclosure at T?
- Oil has the thermal properties of unused engine oil
- The temperature of the inner pipe is constant
SKETCH
PROPERTIES AND CONSTANTS
the Stephan-Boltzmann constant
for unused engine oil at 550 K
Density (p) = 742 kg/m3
Specific heat (c) 2998 J/(kg K)
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What will be an ideal response?
For the same energy, the most penetrating type of radiations in human tissue are ________
a. alpha particles b. beta particles c. gamma rays
Most Greek philosophers believed in a geocentric Universe
a. True b. False Indicate whether the statement is true or false