일반물리학 1 — Gravitation: Problem 27

27 In Fig. 13-29, a square of edge length 20.0 cm is formed by four spheres of masses $m_1 = 5.00\text{ g}$, $m_2 = 3.00\text{ g}$, $m_3 = 1.00\text{ g}$, and $m_4 = 5.00\text{ g}$. In unit-vector notation, what is the net gravitational force from them on a central sphere with mass $m_5 = 2.00\text{ g}$?