An impact crater that is 10 kilometers across was probably made by the impact of an object about ________ across.
A) 10 meters
B) 100 meters
C) 1 kilometer
D) 10 kilometers
E) 100 kilometers
C) 1 kilometer
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A solar collector design consists of several parallel tubes each enclosed concentrically in an outer tube that is transparent to solar radiation. The tubes are thin walled with the inner and outer cylinder diameters of of 0.10 and 0.15 m respectively. The annular space between the tubes is filled with air at atmospheric pressure. Under operating condition the inner and outer tube surface temperatures are 70°C and 30°C respectively.
(a) What is the convective heat loss per meter of tube length?
(b) If the emissivity of the outer surface of the inner tube is 0.2 and the outer cylinder
behaves as though it were a black body, estimate the radiation loss.
(c) Discuss design options for reducing the total heat loss.
GIVEN
? Thin walled concentric tubes with air atmospheric pressure between them
? Inner tube diameter (Di) = 0.1 m
? Outer tube diameter (Do) = 0.15 m
? Inner tube temperature (Ti) = 70°C = 343 K
? Outer tube temperature (To) = 30°C = 303 K
? Outer surface emissivity of inner tube (E) = 0.2
FIND
(a) The convective loss pe meter of tube (qc/L)
(b) The radiative loss (qr/L)
(c) Discuss design options for reducing the total heat loss
ASSUMPTIONS
? Steady state
? Tubes are horizontal
SKETCH
PROPERTIES AND CONSTANTS
A 10 kg bomb is moving NORTH with a velocity of 4.0 m/s. It explodes into three fragments: a 5.0 kg fragment moving WEST with a speed of 8.0 m/s, a 4.0 kg fragment moving EAST with a speed of 10 m/s, and a third 1.0 kg fragment. What is the velocity of the third fragment?
A. zero B. 40 m/s NORTH C. 40 m/s SOUTH D. none of these answers are correct
Which of the following particles (or groups of particles) are made up of quarks?
A) protons, neutrons, and electrons B) electrons and neutrinos C) photons D) protons and neutrons E) All particles except for photons are made up of quarks.
A coil lies flat on a horizontal tabletop in a region where the magnetic field points straight down. The magnetic field disappears suddenly
When viewed from above, what is the direction of the induced current in this coil as the field disappears? A) counterclockwise B) clockwise C) clockwise initially, then counterclockwise before stopping D) There is no induced current in this coil.