Density

Density = mass/volume D = M/V Density is the mass per unit volume of a substance. How much material is packed into a given space. Everything has a density.

Density is how much “stuff” is packed into a given space… Think about it, if you had a suitcase and you stuffed 1,000 pairs of socks into the suitcase, would it be more or less dense than if you stuffed only 100 pairs of socks into that same suitcase?

Balloons and Bowling Balls… Objects of the same volume (space an object takes up) can have very different densities… It depends on their mass, for example, imagine that the bowling ball and the balloon on the right were exactly the same size, which do you think would have a higher density?

Some Things Float… Some Things Sink… A granite rock is more dense than water, so it sinks, while certain pieces of wood may be less dense than water so they float. Heat rises while cold sinks.

The Density of Water Water is very unique. Water is more dense in its liquid form, than its solid form… this is why ice floats.

Convection The transfer of heat within fluids Heat rises while cold sinks Heat moves atoms apart creating a lower density Density’s affects influence weather, volcanic eruptions and ocean currents.

Finding Density Density Mass = Volume M D = m / v V = m / d M = dv D V

How do I find the mass? You find the mass by using a balance…measured in grams.

How do I find volume? Object with smooth flat surfaces like a cube or a rectangle Use Length x Width x Height (L x W x H) Object with uneven, hard to measure surfaces Use displacement (Demo) Difference in water level in a graduated cylinder after the object is added to an existing amount of water.

Return to your equation…plug in your numbers and solve. Density Mass = Volume M Equations D = m / v V = m / d M = dv Units D = g/mL or g/cm3 V = mL or cm3 M = g D V

You have a mineral that has a mass of 32 g and a volume of 4 mL You have a mineral that has a mass of 32 g and a volume of 4 mL. What is the density? Mass = 32 g Volume = 4 mL Density = 32 g / 4 mL Density = 8 g/mL Units D = g/mL or g/cm3 V = mL or cm3 M = g Equations D = m / v V = m / d M = dv

You have a mineral that has a density of 10 g/cm3 and a mass of 62 g You have a mineral that has a density of 10 g/cm3 and a mass of 62 g. What is the volume? Mass = 62 g Density = 10 g/cm3 Volume = 62 g / 10 g/cm3 Volume = 6.2 cm3 Units D = g/mL or g/cm3 V = mL or cm3 M = g Equations D = m / v V = m / d M = dv

You have a mineral that has a density of 7 g/cm3 and a volume of 6 cm3 You have a mineral that has a density of 7 g/cm3 and a volume of 6 cm3. What is the mass? Density = 7 g/cm3 Volume = 6 cm3 Mass = 7 g/cm3 x 6 cm3 Mass = 42 g Units D = g/mL or g/cm3 V = mL or cm3 M = g Equations D = m / v V = m / d M = dv

Volume = displacement -> 28 – 25 = 3 mL Density = 21 g / 3 mL You have an object that has a mass of 21 g. You cannot measure the volume by doing L x W x H. You have use a graduated cylinder. There is 25 mL of water in the cylinder prior to sliding the object in. After you have slid the object in the cylinder shows 28 mL. Mass = 21 g Volume = displacement -> 28 – 25 = 3 mL Density = 21 g / 3 mL Density = 7 g/mL Units D = g/mL or g/cm3 V = mL or cm3 M = g Equations D = m / v V = m / d M = dv