This example created with the kinematics software ASOMv7 shows how the normal forces in the two table legs change or adapt when a horizontal force is applied to move the table.
The right table leg has a wheel, while the left one does not. Thus the left table leg corresponds to a sliding bearing (with a sliding friction coefficient of µ=0.6 for wood on stone), while the right table leg corresponds to a rolling friction (with an idealized rolling friction coefficient of µ=0). Depending on the height at which the force to move the table is applied, it could happen that the right table leg would lift off. This can be inferred from the fact that the measured normal force on the right becomes negative.
German version (no English version available)