Question 12 (3 points) The diagram below shows four objects in the solar system which have equal masses.
1
3
4
2.
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Which of these pairs of objects exerts the least gravitational force on each other? (3 points)
Оа
Ob
Object 1 and Object 3
Object 4 and Object 3
Object 1 and Object 2
Ос
Od
Object 4 and Object 2

If a star is moving toward earth, it is

Hydroelectricity provides about 7 percent of the electricity generated in the united states. (a) explain how a hydroelectric power plant converts energy stored in water into electricity. (b) identify two factors that determine the amount of electricity that can be generated by an individual hydroelectricity power plant. (c) describe the two main types of land-based hydroelectric power plants. (d) describe two economic advantages and two environmental disadvantages of hydroelectricity.

According to piaget’s stages of cognitive development, the child does not differentiate between self and other objects. the child repeats rewarding activities, discovers new ways to get what he or she wants, and may have imaginary friends. which period is described?