Since evaporation of water from reservoirs is an important water loss mechanism, especially in dry climates, it is important to reduce losses. What measures could you suggest for reducing such evaporation? Are any of these actually feasible?
What will be an ideal response?
Clearly, one could entirely cover the reservoir. This is completely impractical
because of the cost of such a system unless a suitable underground reservoir candidate is
available, which would not commonly occur. In earlier days when cities—and thus water
demands—were smaller, reservoirs could be small enough to be covered (there is one such
in Washington, DC, for example)..
It has been suggested that floating ping pong balls could cover the surface and the white
color could reflect incident solar energy. This does appear feasible but costly unless the
surface area to volume ratio is low, but the balls could soon be covered by algae and cease
reflecting, changing water temperature.
The most efficient way to regulate evaporative losses is to minimize the surface of the
reservoir, because evaporation occurs at the surface. A deep reservoir with a small surface
area to volume ratio would probably not need additional efforts to reduce evaporation.
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Two objects are in uniform circular motion at the same speed but at different radii. The one with the ______________ radius has the largest centripetal acceleration
Fill in the blank(s) with correct word
If the voltage on a capacitor is doubled, then the energy stored by the capacitor
A) quadruples. B) doubles. C) halves. D) stays the same. E) triples.
Determine the increase in the open spacing between precipitate particles that occurs when the 2014 aluminum alloy shown in Figure 7.17 is aged for 1000 h at 149°C (300°F), relative to the value at peak strength that is calculated in Example Problem 7.5. Assume that the as-quenched yield strength of 100 MPa is the value of ?0, that the lattice parameter of FCC aluminum is 0.404 nm, and that the shear modulus of this alloy is equal to that of aluminum given in Table 6.1.
What will be an ideal response?
Reactance: A simple ac circuit is composed of a capacitor connected across the terminals of an ac power source. If the frequency of the source is doubled, what happens to the reactance of the capacitor?
A. It increases by a factor of 4.
B. It increases by a factor of 2.
C. It increases by a factor of 
.
D. It decreases by a factor of 2.
E. It decreases by a factor of 4.