It was observed that a small block of mass m remains in equilibrium at the centre of a vertical square frame, which was accelerated. The block is held by two identical light strings as shown. [Both strings are along the diagonal]
(a) Which of 1, 2, 3 & 4 is/are possible direction/s of acceleration of the frame for block to remain in equilibrium inside it?
(b) Find the acceleration of the frame for your answers to question (a).

Answer

(a) 2,4
(b) In both cases acceleration of the frame must be 'g'.