What is the boundary of a black hole beyond which a spacecraft could not even in principle transmit a radio signal to observers outside the black hole.
Answer: The Event Horizon
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An attractive method of energy conservation in industrial settings is to utilize waste heat from largescale power generating equipment. In one such scheme, the exhaust gases from the diesel engine of an industrial power generator are channeled through a cross- flow, compact, waste-heat recovery boiler to produce process steam. In one such heat exchanger, a finned tube bundle is configured with tubes of 2.5 cm outer diameter that are arranged in a staggered equilateral- triangular array with tube center-to-center pitch of 7.5 cm. Engine exhaust gas (thermal properties of which are taken to be the same as those for air) at 400°C is in cross-flow over the tube bank with a free stream velocity of 2.0 m/s. In order to enhance the gas-side convective heat transfer, the tubes have thin circular
fins on their outer surface and the finned surface extension ratio ?=1.15. Due to the steam generation process inside the tubes, their outer surface temperature is 175°C. If there are 10 rows of tubes in the flow direction (NL = 10), calculate the average heat transfer coefficient and pressure drop for the gas flow stream.
GIVEN
FIND
The average heat transfer coefficient (c h) and pressure drop in gas flow stream.
ASSUMPTIONS
Steady state
Tube wall temperature is uniform and constant
SKETCH
PROPERTIES AND CONSTANTS
The equation below is the solution to a problem.
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.
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The best physical representation of this equation is
A. a sphere of 2.00-kg mass under a 6.00-N tension when at the bottom of a vertical circle. B. a sphere of 2.00-kg mass under a 6.00-N tension when at the side of a vertical circle. C. a sphere of 2.00-kg mass under a 6.00-N tension when at the top of a vertical circle. D. a sphere of 2.00-kg mass at any point on a horizontal circle. E. a 2.00-kg gecko running on the ceiling with a speed of 8.00 m/s.
Two parallel conductors each of 0.50-m length, separated by 5.0 × 10^-3 m and carrying 3.0 A in the same direction, will experience what type and magnitude of mutual force? (magnetic permeability in empty space µ0 = 4p × 10^-7 T×m/A)
a. attractive, 1.8 × 10^-4 N c. repulsive, 0.60 × 10^-4 N b. repulsive, 1.8 × 10^-4 N d. attractive, 0.06 × 10^-4 N
Light of wavelength 500 nm illuminates a soap film ( n = 1.33). What is the minimum thickness of film that will give an interference maximum when the light is incident normally on it?
A) 24 nm B) 94 nm C) 188 nm D) 279 nm E) 376 nm