Question

A square wooden block open from one side is lying on a horizontal table. Different weights are kept in the box one by one. To establish the relationship between weight of a block and the minimum force required to just move tit using a spring balance, it is observed that the force required to just move the square block is minimum when we put a weight of:-

(a) 35 gwt
(b) 40 gwt
(c) 30 gwt
(d) 45 gwt

here gwt is gram weight...