Consider the situation shown in figure
(6-E9). Suppose a small electric field E exists in the space in the vertically upward direction and the upper block carries a positive charge Q On its top surface. The friction coefficient between the two blocks is μ but the floor is smooth. What maximum horizontal force F can be applied without disturbing the equilibrium?
[Hint: The force on a charge Q by the electric field E is F = QE in the direction of E.]
R1 is the normal reaction force
Q is the charge
E is the small electric field
From the free body diagram, figure (b)
From figure (a)
From equation (i) and (ii)
Equation (ii) can be written as,
Hence, maximum horizontal force which can be applied =
1