Why did the atmosphere of Venus develop differently from that of Earth?
What will be an ideal response?
Calculations show that Venus and Earth should have outgassed about the same amount of carbon dioxide, but Earth's oceans have dissolved most of Earth's carbon dioxide and converted it to sediments such as limestone. This suggests that the main difference between Earth and Venus is the lack of water on Venus that would have removed carbon dioxide from the atmosphere. There is evidence that Venus had oceans when it was young, but being closer to the Sun it was warmer, and the carbon dioxide in the atmosphere created a greenhouse effect that made the planet even warmer. That process could have vaporized any oceans that did exist and reduced the ability of the planet to purge its atmosphere of carbon dioxide. As more carbon dioxide was outgassed, the greenhouse effect grew even more severe. Thus, Venus was trapped in what is called a runaway greenhouse effect.
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Reconsider the problem described in where water jets from a nozzle that has a diameter of 6 mm and impinges on a disk of 4 cm in diameter that is subjected to a uniform heat flux of 70,000 W/m2. Instead of water, consider using air and ethylene glycol as the cooling fluids with the same flow rate (0.008 kg/s) and temperature (20°C) in each case, and determine the temperature on the surface of the disk at radial distances of 3mm and 12 mm from the axis of the jet. Compare the results with those for water obtained in and comment on them.
GIVEN
FIND
(a) Temperature on the surface of disk at radial distance of 3 mm and 12 mm from axis of jet.
(b) Compare results with those of water obtained
PROPERTIES AND CONSTANTS
An elastomeric bearing pad is subjected to a shear force V during a static loading test. The pad has dimensions a 5 150 mm and b 5 225 mm, and thickness t 5 55 mm. The lateral displacement of the top plate with respect to the bottom plate is 14 mm under a load P 5 16 kN. The shear modulus of elasticity G of the elastomer is approximately:
(A) 1.0 MPa
(B) 1.5 MPa
(C) 1.7 MPa
(D) 1.9 MPa
A copper pipe is held vertically and a magnet is dropped down the pipe. The magnet is oriented with the north pole down. What direction do the Eddy currents flow as viewed from above the pipe? If copper bar of approximately the same size and weight is dropped down the tube will it fall faster or slower?
A. CCW above the magnet and CW below the magnet; copper bar will fall slower B. CCW above the magnet and CW below the magnet; copper bar will fall faster C. CW above the magnet and CCW below the magnet; copper bar will fall slower D. CW above the magnet and CCW below the magnet; copper bar will fall faster
The figure shows a graph of the velocity as a function of time for a basketball player traveling up and down the court in a straight-line path. For the 10 s shown on the graph, find (a) the net displacement of the player. (b) the total distance run by the
What will be an ideal response?