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Measuring Matter

Weight is a measure of the force of gravity on a person or thing.

On Earth all objects are attracted downward by Earth’s gravity.

In everyday life, weight is a useful measurement of how much matter an object contains.

Mass vs. Weight

On other planets or on the moon, the force of gravity is far less or even non-existent.

Scientists rely on a property that is consistent regardless of where the object may be located and this property is called mass.

Mass is the measurement of how much matter an object contains.

An object’s weight will change if you move it from Earth to the moon or to other planets, but its mass will stay the same.

To measure the properties of matter, scientists use a system of units called the International System of Units. (SI)

For mass, the SI unit is the kilogram (kg).

Although you may see things measured in kilograms, the most common way to measure mass is in grams. (g)

There are exactly 1000 grams in one kilogram

Units of Mass

The amount of space that an object takes up is called volume.

It is easy to see the amount of space a solid or a liquid takes up, but gases are have volume too.

When you blow up a balloon you can see that your breath has volume.

To find the volume of a rectangular object the following equation must be used: Volume= Length X Width X Height.

Volume

If the object is measured using centimeters, the final unit will be cubic centimeters. (cm3)

Other common units of volume are liters (L) and milliliters (mL).

A milliliter is exactly 1 cubic centimeter and there are 1000 milliliters in one liter.

To find the volume of an irregular shaped object, the object can be placed in a graduated cylinder containing water.

Measure the amount of water in the graduated cylinder before the object is placed in the water and after the object is placed in the water.

Subtract the first reading from the second reading to find the object’s volume.

https://www.youtube.com/watch?v=n3ia4i-uFTM

Different substances may have the same mass, but they don’t necessarily fill the same volume.

Density is the measurement of how much mass is contained in a given volume.

To calculate the density of an object, divide its mass by its volume.

Density= Mass/Volume

Density

One typical unit of density is written as g/cm3.

The density of a substance is the same for all samples of that substance.

For example, all samples of gold regardless of size have a density of 19.3 g/cm3.

Density is another example of a characteristic property.

https://www.youtube.com/watch?v=kE8I_M2pyg8

  http://phet.colorado.edu/sims/density-and

-buoyancy/density_en.html

http://phet.colorado.edu/en/simulation/states-of-matter-basics

Links to Check Out

Why are mass and weight different measurements?

  What two quantities do you need to

know in order to calculate density?   Describe how you would measure the

volume of an object with a n irregular shape.

 

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