# Scientific Measurement & Common Instruments

Instructor: Julie Zundel

Julie has taught high school Zoology, Biology, Physical Science and Chem Tech. She has a Bachelor of Science in Biology and a Master of Education.

While you've probably measured something, you may not be familiar with some of the scientific instruments that help us measure length, volume, mass, and time. This lesson will explore some common and not so common scientific instruments to help you understand the world of scientific measurement.

## Measuring in Science

You may have measured many things in your life, whether it be the gallons of gas you put in your car, your shoe size, how far you ran for your workout, or even your height. Measuring in science is a lot like measuring in the everyday world, but with a little more detail and some unique instruments.

Scientists use the metric system, which uses the following base units:

• Meter for length
• Gram for mass
• Liter for volume
• Second for time

Different prefixes (the letters before the base unit) are used in the metric system to denote how many base units something contains. For example, a kilometer is 1000 meters, a milliliter is 1/1000th of a liter.

Prefix Meaning
kilo 1000
hecto 100
deka 10
base unit 1
deci 0.1
centi 0.01
milli 0.001

Now that you have some metric system terminology under your belt, let's go on a science tools tour.

## Measuring Tools for Length

Let's start with tools you would use to measure length or the distance between the two points.

When you need to measure length you might use a ruler. This is a straight piece of material, generally wood, plastic, or metal, with calibrated lines for measuring distance.

Vernier calipers may not be a tool that comes to mind. While this can be used to measure length like a ruler, it is often used to measure the thickness and diameter of objects like pipes. This tool is more precise than a ruler and it is made up of an arm and a jaw.

Let's zoom in to see what the measurement is and briefly go over how to read this type of tool.

• Make sure the object is snug between the 'jaws' of the caliper (Image 3). Read the main scale on the calipers. Here it is 3.
• Next, see which little line (in this case a millimeter) lines up with the 0. Here it is 5 (each line is 1). So our current reading is 3.5 cm.
• Look for alignment between the two scales (Where on the centimeter (cm) scale and the millimeter (mm) scale do the lines line up?). If you look closely, the 2 on the mm scale lines up with the cm scale. So this means 0.02.
• Add up the values you have: 3.5 + 0.02 = 3.52. Don't forget the units: 3.52 cm.

Let's continue our science tools tour with the micrometer screw gauge. This is another tool used to measure length, specifically the diameter of objects like wire. It can also be used for other measurements. This measuring tool is u-shaped and the object needing to be measured is held snuggly with a screw. Reading it is very similar to reading a Vernier caliper.

## Measuring Tools for Volume

Now that you're familiar with a few tools used to measure length, let's check out tools for measuring volume, or the amount of space an object takes up. There are several tools that can be used to measure volume, such as a graduated cylinder (Image 5). Our focus here will be finding the volume of a solid by using displacement, looking at how much fluid is 'displaced' when an object is placed in water. Think about filling a bathtub full and then climbing in. What happens? It overflows. This is because you displaced the water with your volume, which caused the tub to overflow.

To measure using this technique you need to do the following:

• Place water in a graduated cylinder and record this number as 'starting volume.'
• Add the object to the water and record the new number as 'final volume.'
• To find the volume of the object you subtract: final volume-starting volume

## Measuring Time

So far our tour has highlighted science tools in the world of length and volume, but now let's check out how to measure time or the duration of an event.

Oftentimes a stopwatch or a watch that has buttons that can start and stop it works well. Most stopwatches can measure time in milliseconds, seconds, minutes and hours.

Another tool used to tell time is a simple pendulum, which is constructed from a string attached to a fixed surface that allows it to swing. On the other end of the string is a weight called a bob.

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