 The problem reads 4 meters cubed of oil weighs 31.5 kilonewtons. Calculate its mass density row, its specific weight gamma, and its specific gravity SG. As always, let's write down what we have. We have 4 meters cubed. That's volume. And we have a weight of 31.5 kilonewtons. Now, before I get going with calculating, I like to make this into people language. If you don't, click on the link here, and you can go directly to the calculations. I know that in people language, that is on a scale, if I were to weigh 100 kilograms, thank goodness I don't, that would be approximately 1 kilonewton really weight, right? So if the scale shows 100 kilograms, that means I really weigh 1 kilonewton. So what is my mass here approximately? It's m approximately equal to 31.5. And instead of kilonewtons, I will write 100 kilograms, which is 3,150 kilograms. So for 4 meters cubed of oil, I have approximately 3,150 kilograms. That's lighter than water, because if it was water, it would be 4,000 kilograms. So we're looking at something that's lighter than water. And we should keep that in mind. Okay, now let's go to our formulas and do our calculations. So here are our formulas. And so what do we have? We have weight and volume. What's the easiest thing to calculate first with weight and volume? The specific weight, gamma. So gamma equals weight over volume, so 31.5 kilonewtons over 4 meters cubed. And get a calculator. So we have 31.5, and we're going to write it Newton. So we have E3 divided by 4 equals 7,875. 7,875 newtons per meter cubed. So that's the answer to what is gamma. Okay, let's move on to rho. We can get rho now, because rho is equal to gamma divided by g. We know gamma, and we know g. So rho equals gamma divided by g, the gravitational force, which is 7,875 newtons versus meters cubed over 9.81 meters per second squared. Equal to, let's divide our two numbers. So we have our answer, so we just divide it by 9.81. And we get 802. We have newtons versus meters per second squared times 1 over meters cubed. And this is kilograms. So we have rho equals 802 kilograms per meter cubed. Does that make sense? The answer is yes. The density of water is 1,000 kilograms per meter cubed. We have lighter than water. We have only 800. That's good. So this is our answer to rho. And then sg is equal to, this is going to be a unit list thing, because it's just one rho over another rho. It's our 802 kilograms per meter cubed over 1,000 kilograms per meter cubed. This is water, our substance over our water. And of course, that's just 0.8. And that's it, 0.8. So this is the answer to the third part of the problem. No units, 802 kilograms per meter cubed, that's good for density. Newtons per meter cubed, that's good for specific weight. Everything is in good shape.