Three equal masses m are placed at the three corners of an equilateral triangle of side α. Find the force exerted by the system on another particle of mass m placed at
(a) The mid-point of a side,
(b) At the Centre of the triangle.
(a)From the figure, the forces exerted by particles O and Q are equal and opposite. Hence, only particle P is exerting a force on A.
Distance between particle P and A is
Therefore, the force is given by
(b) At the midpoint (B), the gravitational forces from the particles are equally balanced in all directions. Hence, the total force is zero.