(COP) Making Measurements and Calculating Data Lesson

Making Measurements and Calculating Data

Physics is the study of nature, specifically focusing on matter and energy. To explain and model physical systems in nature, mathematical relationships are often used in physics. By giving numerical values for physical principles, it allows for a deeper understanding of nature.  When expressing measurements, it is important to have a standardized system to represent given quantities.  Without a standardized system, it would be extremely difficult for scientists to compare measured values in a meaningful way.

Comparing Measurements Chart: English Miles Feet Inches Ounces Pounds Gallon Pints Metric Kilometers Meters Centimeters Grams Kilograms Liters MillilitersThe metric system is the standard system agreed upon by scientists.  What is the metric system? It is actually the standard system for measuring used worldwide.  Very small and very large objects are expressed as multiples of ten of the base unit.  According to Anthony Carpi at VisionLearning, the Metric System has been around since 1790 . Although the Metric System is not commonly used in the United States, scientists have gladly embraced it as a system to help them take exact measurements.  What makes it so popular among scientists? To begin with, it is remarkably easy to use. In this course, you will be making measurements. Scientists make and use measurements all the time, but did you know that we also use measurements in our everyday lives?

Take a minute to think about how many measurements you use each day.  How much sugar should be added to make blueberry muffins?  How fast do you drive?  How much time will it take you get home from school? How much money will it cost to buy a snack after school?   When you think about the answers to these questions, you most likely think in units of the English system.  In this course, you will be required to use the metric system. To get yourself more familiar with the metric system, start looking for metric units as you go about your day. Look at the labels on the food you eat and drink, the personal care and cosmetic items you use, the kilometers on your speedometer, and more.  

Length

The base unit for length, or distance, in the metric system is the meter.  A meter stick is used to measure length.  When measuring smaller or larger distances, prefixes are used.   For instance, 1 kilometer is equal to 1000 meters.  For measuring smaller items, millimeters are used.  One meter is equal to 1000 millimeters.  A kilometer would be used to measure long distances, like those equivalent to a mile.  A millimeter would be used to measure short distances, like the width of a dime.  When using the metric system, you must be familiar with the prefixes used to denote the size of the unit as seen in the table below:

Measurement Prefixes

 

Prefix

 

Size Compared to Base Unit

 

Abbreviation

Kilo

1000 x's Larger

k

Hecto

100 x's Larger

h

Deca

10 x's Larger

da

Base Unit

1

Meter (m), Liter (L), Gram (g)

Deci

.1 x's Smaller

d

Centi

.01 x's Smaller

c

Milli

.001 x's Smaller

m

Here are some good examples of when to use the varying units:

  • The size of an ant would be measured in centimeters
  • The length of your deck would be measured in meters.
  • The distance to your school would be measured in kilometers.

The presentation below will discuss reading a triple beam balance. 

Mass

Mass is another important measurement made by scientists.  Mass is the amount of matter in an object.  In other words, it's the amount of stuff that the object is made up of.  The base unit for mass is grams.  Mass is measured by using a triple-beam balance.  Mass and weight are not the same thing, although they are commonly referenced interchangeably.  Mass is the amount of matter (stuff) that makes up an object while weight is the measurement of the force due to gravity.  It can be confusing to see the difference between the two because everything we do takes place on Earth. However, if you traveled to the moon you would be able to see the difference. Your mass on the moon would remain the same (how much matter you are made up of). However, your weight on the moon would be significantly less because the force of gravity is less on the moon. We will visit this topic again in the next module. Here are some examples of when you would use the varying units:

  • The mass of a strand of hair would be measured in milligrams.

  • The mass of a raisin would be measured in grams.

  • The mass of your dog would be measured in kilograms.

Volume

image of cylinders for measuring volumeVolume is a measurement of how much space an object takes up. The base unit for volume is the liter.  Liquid volume is measured by using a graduated cylinder.  The volume of a regularly shaped object, like a cube, is measured by multiplying length x height x width. When you multiple these 3 dimensions (centimeters x centimeters x centimeters) you get centimeters cubed.   It is important to know that 1 cm3   = 1 mL.  Sometimes these units are used interchangeably for volume.   To find the volume of an irregularly shaped object, like a rock, you would need to use the water displacement method.  Since you cannot easily measure the length, height, and width; you would want to see how much space it takes up by seeing how much space it takes up in water.  To do this, you measure a certain amount of water; let's say 20 mL.  Then you place the irregularly shaped object in the given amount of water and see how much the water rises. Let's say when we place the rock in 20 mL of water, the water rises to 23 mL.  What does this tell us?  What is the volume of the rock?  Since the water rose 3 mL that means volume of the rock is 3 mL.  Here are some examples of when you would use the varying units:

  • The amount of liquid a medicine dropper holds would be measured in milliliters.  
  • The amount of liquid in a Coke-cola bottle would be measured in liters.

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