Lab 1: Measurement, Precision, and Accuracy

Physics is a science. Scientists watch things. Scientists test things. We measure many things in physics. We measure length. We measure how much space something takes up. We measure weight. We measure heat.

Good measuring is important. We want our measurements to be careful. We want them to be correct.

Let's think about a string. Say the string is 30.48 centimeters long. That is the true length.

Accuracy means how close you get to the true number. Measure the string three times. Do you get close to 30.48 each time? If yes, your measuring is accurate.

Precision means your measurements match each other. Do your three measurements look almost the same? If yes, your measuring is precise.

In this lab you will learn:

• How to measure how much space something takes up.
• How to measure weight with different tools.
• How to measure length with rulers and string.

Activity 1: Measuring Volume

Volume means how much space something takes up.

You will measure three objects. You will use a special tube with marks on it.

You will learn a new trick too. It is called the displacement method. Here is how it works. You put water in a container. You know how much water is there. Then you put an object in the water. The water goes up! The water rises because the object takes up space. This tells you the object's volume.

This trick is great for odd shapes. Some objects are hard to measure with a ruler. The water trick still works!

When you measure, you read numbers from your tool. These numbers are called significant figures. They show how careful your measurement is.