A lump of pure copper weighs 25.155 in air and 22.434 when submerged in water ( = 0.9982 ) at 20.0 . Suppose the copper is then rolled into a 245- foil of uniform thickness. What will this thickness be, in millimeters? I don't understand how your supposed to figure this out! Please help.
Indirectly when you put the copper in water, you are given the volume. The bouyancy force lightens the copper by an amount almost equal to it's volume because the water pushes up on it. So let's go. Step One. ======= Find the weight difference in air and water. Copper weighs (in air) = .....25.155 grams Copper weights (in H20) = ..22.434 grams Difference = ........................2.721 grams Step Two ======= Find the volume of water pushed aside (and thus creating an upward buoyancy force). d = .9982 g/cm^3 m = 2.721 grams V = ? V = m/d V = 2.721/0.9982 V= 2.726 cm^3 Step Three ======== drat!! I don't know what the units of 245 is. I will guess they are cm^2 thickness = ? Volume = 2.726 cm^3 Area = 245 cm^2 2.726 = area*thickness 2.726 = 245 * thickness 2.726/246 =thickness thickness = 0.0111 cm or 0.111 mm
add 25.155 and 22.434 then divide by 0.9982 and then multiply again by 245. The quantity of x+3 will lead this to your answer. I know this because i graduated from harvard.
