A person uses corrective glasses of power -8.5 D that are worn 2.0 cm from her eye
(a) Is she nearsighted or farsighted?
(b) What is her far point without glasses?
(a) nearsighted (b) 14 cm
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An important reason that sedimentary rocks are economical is that they are porous and permeable. Natural gas, for example, collects in the pore spaces between the sediment grains within these rocks. Porosity is the amount of space between the grains within a rock. It can be quantified as the total volume of space between grains divided by the volume of grains. A low porosity means that there is little space, and a high porosity means that there is a lot of space. -Permeability is how much the pore spaces are connected. Fluid flows through rocks that are more permeable.
The image below is an illustration of two different rocks. These images are magnified to show the individual grains (dark gray) and pore spaces (light gray) that make up the rock. Study these images and select the statement that describes the correct comparison of the porosity and permeability of these two rocks.
A.) Rock A has a lower porosity and a lower permeability than Rock B.
B.) Rock A has a higher porosity and a lower permeability than Rock B.
C.) Rock A has a lower porosity and a higher permeability than Rock B.
D.) Rock A has a higher porosity and a higher permeability than Rock B.
One reason the planets near the Sun are composed mainly of rock and iron may be that
A. the Sun is made mostly of iron, so the planets nearest it are formed of iron. B. the Sun's heat made it difficult for ices and gases to condense near it. C. the Sun's gravity sucked in iron and heavy material and the lighter materials floated farther away. D. the Sun's magnetic field attracted all the iron into the region around the Sun.
Suppose that Earth's atmosphere had no greenhouse gases. Then Earth's average surface temperature would be ________
A) well below the freezing point of water B) slightly cooler, but still above freezing C) slightly warmer, but still well below the boiling point of water D) about the same as it is now
As long as there is ice in your drink, the temperature of the ice remains near
a. room temperature. b. the temperature of the drink. c. zero Celsius. d. zero Fahrenheit.