A package of aluminum foil contains 50ft^2 of foil, which weighs approximately 8.0ozAluminum has a density of 2.70 g/cm^3What is the approximate thickness of the foil in millimeters?
this problem requires you to know the density formula as well as make conversions into a standard set of units first, recall that density mass/volume you are given the density and the mass, so we can find the volume from: volume mass/density first, let's convert the mass (they are actually giving you a weight, but let's not quibble) from ounces to gramsthere are 453.6 grams/lb and 16 ounces per pound, so there are 28.35 grams/ounce and therefore 226.8 grams in 8 ouncesThis tells us that the volume of the foil is volume 227.6 g/ 2.7 g/cm^3 84.3 cm^3 now, how do we get the thickness of the foil? The volume of the foil is just its area times its thickness, so we know that volume area x t where we want to solve for t, the thickness first, we convert 50 ft^2 to cm^2: 1 ft^2 12 in x12 in 144 in^2 1 in^2 2.54 cm x 2.54 cm 6.45 cm^2 so that 1 ft^2 144 x 6.46 cm^2 929 cm^2 and 50 ft^2 46,451 cm^2 so, we now know volume 46,451 x t and this equals 84.3 cm^3 thus: t 84.3 cm^3/46,451cm^2 0.0018 cm 0.018 mm
i would never use faced ins in an attic in the first placei agree on the r13 whole atticother thing is to make sure you have good ventilation from the eaves to the top of the roofif you dont/cant then an attic vent or some type of power vent should be used to get the heat outeven with insulation the heat will make it into the housethe attic needs to breathe
