Walker, Halliday & Resnick — Gravitation: Problem 14

14 The three spheres in Fig. 13-24, with masses \( m_A = 80\text{ g} \), \( m_B = 10\text{ g} \), and \( m_C = 20\text{ g} \), have their centers on a common line, with \( L = 14\text{ cm} \) and \( d = 2.0\text{ cm} \). You move sphere B along the line until its center-to-center separation from C is \( d = 2.0\text{ cm} \). How much work is done on sphere B (a) by you and (b) by the net gravitational force on B due to spheres A and C?