Passage III

Earth's gravitational field extends both above and below Earth's surface. In Figure 1, both the value of this field, , and the average density, ρ, of matter within Earth are graphed versus distance, r, from Earth's center. In addi­tion, Figure 1 identifies 5 regions, each of which is located either above or below Earth's surface.

Figure 2 shows the percent of Earth's mass located within a given distance r from Earth's center. For example, 10% of Earth's mass is located within 2,300 km of Earth's center, 20% of Earth's mass is located within 2,900 km of Earth's center, and so on.

Figures adapted from A. M. Dziewonski and D. L. Anderson, "Pre­liminary Reference Earth Model."©1981 by Elsevier B.V.

19. Consider 2 hypothetical 1 kg rocks: one located at r = 2,000 km and the other located at r = 4,000 km. Based on Figure 1, which of these 2 rocks, if either, more likely weighs less ?

Answer and Explanation

Your Answer is

Correct Answer is A

Explanation

weight W=mg, so the mass is the same, just look at the gE of the two positions, the smaller the gE, the smaller the W;

Look at figure 1, when the abscissa r=2000 km , gE is about 7; when the abscissa r=4000 km, gE is about 10. Therefore, the gE at 2000 km is smaller, and the Weight will be smaller