Chapter 1 Lesson 2Measurements in Science

Key Vocabulary

Metric System

International System of Units (SI)

Mass

Weight

Volume

Density

A standard measurement system is important because it allows scientists to compare data and communicate with each other about their results.

Metric System

The Metric System is a measurement system based on the number 10.

Modern scientists use a version of the metric system called the International System of Units (SI).

Length

A Meter (M) is the basic SI unit used for measuring length.

One tool used to measure length is a metric ruler.

Example: You can measure how far you kick a soccer ball in meters.

Mass

Mass is a measure of the amount of matter in an object.

In SI, the basic unit for measuring mass is the Kilogram.

Things that you would measure in kilograms are the mass of: Cars, Bikes, and People. (larger masses)

Weight

Weight is different than mass.

Weight is a measure of the force of gravity acting on an object.

A scale is used to measure weight.

When you stand on a scale, gravity pulls you downward.

Weight and mass are different because The mass of an object stays the same, and the weight of an object changes.

EXAMPLE: On the moon the force of gravity is weaker than on earth. So you weigh less on the moon than you do on earth, but your mass is the same no matter where you are.

VOLUME

Volume is the amount of space an object or substance takes up.

All objects with mass whether they are solids, liquids, or gases, have volume.

In SI, the common units for measure the volume of solids include the cubic meter (m3), and the cubic centimeter (cm3).

Density

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

Density is made up of two measurements, mass and volume.

Because of that the SI unit for measuring density is kilograms per cubic meter.

Temperature

Temperature is measured using a thermometer.

A thermometer has numbers and units, or a temperature scale on it.

There are two temperature scales that are used in science:

The Celsius scale, and the kelvin scale.

THE KELVIN SCALE IS THE BASIS FOR THE SI TEMPERATURE UNITS, AND THE KEVLIN IS THE SI UNIT FOR TEMPERATURE.

TIME

Time is a measurement of the period between two events.

The SECOND is the SI unit used to measure time.

Clocks and watches are used to measure time. Some clocks are more accurate than others.