<span>Its the impact theory.
It suggests that the moon resulted from the collision of two protoplanets, or embryonic worlds. One of those was the just-forming Earth, and the other was a Mars-size object called Theia. The moon then coalesced from the debris, thus giving it its irregular shape.</span>



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If west means the west of the axis x the velocity equal :

The Cell Membrane is what controls what enters and leaves the cell.
It is salt water because they are two things combined together.
Answer:
Almost all machines require energy to offset the effects of gravity, friction, and air/wind resistance. Thus, no machine can continually operate at 100 percent efficiency.