Given that the tensile strength of aluminum foil is 311 megapascals, its thickness is approximately 15.0 micrometers, and a roll of household aluminum foil is 30.0 centimeters wide, how much force f is needed to pull off a sheet to use? assume that the force is applied equally along the whole width of the foil, and that you are trying to pull perpendicular to the cross section. express your answer in newtons to three significant figures.