Measuring Volume

Measuring Volume

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Volume

Volume is defined as the amount of space an object takes up. Because matter takes so many different forms, volume can be measured many different ways.

Multiple Choice

The amount of space an object takes up is called

• mass

• weight

• volume

Cube or Rectangle

To measure the volume of a cubed or rectangular shaped solid all you need is a ruler. Measure the length, width, and height of the object and then multiple the three numbers together.

Volume = length x width x height

Example

Take a look at the orange cube on the right. Notice that the length is 6 cm, the width is 4 cm and the height is 7 cm. So if you multiple those three numbers together you get 168 cm³.

Practice

Now you try calculating the volume of the cube on the right.

Fill in the Blanks

Open Ended

How do you measure liquid volume using a Graduated Cylinder?

Graduated Cylinder

Graduated cylinders are the tools used to measure liquid volume. Graduated cylinders are tall, thin tubes with evenly spaced measurements labeled up the side. The measurements are in milliliters (mL). You might be familiar with 2-liter bottles of soda. One liter is equal to 1,000 mL, so a 2-liter bottle of soda has 2,000 mL!

Meniscus

When a liquid is poured into a graduated cylinder, a little bit of the liquid sticks to the sides and forms a curve. This curve is called a meniscus. When taking the measurement of a liquid, make sure to measure at the bottom of the meniscus.

Practice

Another thing to consider when finding the volume of a liquid is the markings on the graduated cylinder. Look at graduated cylinder in the practice problem. The two lines that are marked are 6 mL and 8 mL. That means that each marking between 6 mL and 8 mL is equal to 0.2 mL. Graduated cylinders are often marked differently, so don't forget to check!

Multiple Choice

What is the volume of the water in this photo?

• 6mL

• 6.4mL

• 7mL

• 6.6mL

Water Displacement

Now that you can find the volume of a liquid, you can find the volume of an irregular solid. How would you find the volume of a rock? It wouldn't be very easy to use a ruler because rocks can have so many different shapes. Instead, you can use a method called water displacement.

Procedures to find the volume of an irregularly shaped object using water displacement:

• Start with a known amount of water and record the volume.

• Place the object in the water and record the new volume of the water.

• Subtract the first volume from the second volume and that will give you the volume of the object.

Take a look at the picture of the graduated cylinders on the left.

The cylinder starts with 200 cm³ of water.

When the rock is dropped in, the volume goes to approximately 270 cm³. (1mL=1cm3)

If you subtract 200 cm3 from 270 cm³ you get 70 cm³.

So the volume of the rock is 70 cm³.

Practice

Now you try to find the volume of a fish using water displacement.

Multiple Choice

What is the volume of the fish?

• 40mL

• 6mL

• 38mL

• 8mL