the mass of a sheet of metal varies jointly with it area and it thickness. a sheet of metal of area 250 cm square and thickness 1nm has a mass of 200g find the formula witch connect the madd mg the area A cm square and the thickness tmm
m = k * area * thickness
200 g = k * 250 cm^2 * 1 nm
so k = (200/250) grams/cm^2 nanometer
and
m in grams = 0.8 * A in cm^2 * t in nanometers