16. 半隱鳩尾榫，其鳩尾榫長度應為板厚的 (A)2/5 (B)2/3 (C)1/3 (D)1/2。

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