An experimental method to locate the three-dimensional coordinates of the center of mass begins by supporting the object at three points and measuring the forces, F 1, F 2, and F 3 that resist the weight of the object, W = − − W k ^ ^ ( k ^ ^ is the unit vector in the vertical direction). Let r 1, r 2, and r 3 be the position coordinates of the support points, then the coordinates R of the center of mass satisfy the condition that the resultant torque is zero, T = ( r 1 − − R ) × × F 1 + ( r 2 − − R ) × × F 2 + ( r 3 − − R ) × × F 3 = 0 , or R × × ( − − W k ^ ^ ) = r 1 × × F 1 + r 2 × × F 2 + r 3 × × F 3 .