 Okay, cool. Now that we've got lunch, let's continue along with these density of un-solved problems. So this first one or whatever says an unknown metal brick with dimensions of 5.08 centimeters by 10.2 centimeters by 20.3 centimeters has a mass of 11.9 50 kilograms What is the density of this metal and units? grams per cubic Okay, so the first thing you want to do is write down what you know So it gives you the volume in this But it gives you the volume length times width times height. So when it says 5.08 centimeters by 10.2 centimeters 20.3 centimeters What it's doing is giving you The thickness and the width and the length or the length with time, you know So just multiply all of those together and if you didn't know that you should remember that centimeters cubed is the units of volume for Solid objects, so if you multiply centimeters times centimeters times centimeters, of course, you're gonna get a Number that has the units of centimeters cubed. So Let's just multiply these things out. So 5.08 times 10.2 times 20.3 And I got So that's too many sig figs because all of these are three sig figs But eventually we're gonna find the density. So that is not the end answer So we're not gonna worry about putting this to the right number of sig figs But the final answer will put the right number of sig figs It also gave us the mass of this object this break it said 11.9 Five zero. It's not grams. Remember one the density and grams per Cubic centimeter, but we do know the conversion. That's a conversion. You're supposed to memorize. Okay, so What is it one kilogram? equals 1,000 grams, excuse me That'll have kilograms cancel and so Three zero so one two three if you can't do that just do it on your calculator eleven point nine five zero times one thousand That's gonna give you eleven nine five zero Grams, of course the density is The mass divided by the volume. So the mass is eleven eleven nine five zero divided by seven centimeters cube and so that's going to give us grams per centimeters cube, which is the unit that we want So we just take that number divided by 11 point so it says on my calculator eleven point three six zero seven seven five six blah blah blah blah but remember we've got to go to the Number with the least number of sick food. So this is three three three and this has five so Three is what we're going to so we've got to round this up to 11 point four grams per so That's the density of this particular unknown metal so what we'll do in a later problem Is compare this to a list of deaths at the densities and figure out what these unknown metals may be