17. 夾背鋸操作施力的方式為 (A)推拉皆可 (B)視情形而定 (C)推 (D)拉。

Problem of 1and 2:Three identical stars, each star's mass is M, form an equilateral triangle that rotates around the triangle's center as the stars move in a common circle about that center. The triangle has edge length L. (The gravitational constant is G)1. What is the net force on each star?(A)2(GM²/L²) (B)(C)(GM²/L²)/2 (D)(E)None of the above