A child slides across a floor in a pair of rubber-soled shoes. The friction force acting on each foot is 20.0 $mathrm{N}$ . The foot-print area of each shoe sole is $14.0 mathrm{cm}^{2},$ and the thickness of cach sole is 5.00 $mathrm{mm}$ . Find the horizontal distance by which the upper and lower surfaces of each sole arfset. The shear modulus of the rubber is 3.00 $mathrm{MN} / mathrm{m}^{2}$ .