An alternative to the nebular theory for the formation of the solar system suggests that the planets formed from blobs of gas that had been gravitationally pulled out of the Sun during the near-collision with another star
This idea is referred to as the A) fragmentation hypothesis
B) collision-ejection hypothesis
C) encounter hypothesis
D) tidal distortion hypothesis
C
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According to the Hubble law, the relationship between the distances to galaxies and the apparent velocity of recession is _____
A) linear B) exponential C) quadratic D) inverse
Meters: A galvanometer has an internal resistance of 100 ? and deflects full-scale at 2.00 mA. What size resistor should be added to it to convert it to a milliammeter capable of reading up to 4.00 mA?
A. 50.0 ? in series B. 50.0 ? in parallel C. 100 ? in series D. 100 ? in parallel
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 20.0 kg box slides down a 12.0 m long incline at an angle of 30.0 degrees with the horizontal. A force of 50.0 N is applied to the box to try to pull it up the incline. The applied force makes an angle of 10.00 degrees to the incline and above the incline. If the incline has a coefficient of kinetic friction of 0.100, then the increase in the kinetic energy of the box is
A. 203 J. B. 275 J. C. 300 J. D. 392 J. E. 425 J.