When the Moon is in its third-quarter phase, the Earth, Moon, and Sun form a right triangle,

Question:

When the Moon is in its third-quarter phase, the Earth, Moon, and Sun form a right triangle, as shown in Figure 12-34. Calculate the magnitude of the force exerted on the Moon by

(a) The Earth

(b) The Sun.

(c) Does it make more sense to think of the Moon as orbiting the Sun, with a small effect due to the Earth, or as orbiting the Earth, with a small effect due to the Sun?

Figure 12-34