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Introduction to Physical Science/1.4

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Experimentation

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This section is primarily concerned with the methods behind taking basic measurements and drawing conclusions. Measurements are pieces of information that are gained by using tools directly. Conclusions are information gained by using calculations and reasoning that are based on Data.

Measurement

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The following sections will teach you how to use the tools you have to measure the indicated basic units.

Barrel (measurement), unit of capacity or volume in the United States and the United Kingdom, the definition of which depends on the material being measured. In the United States the dry standard barrel is equivalent to 105 dry qt, or 7056 cu in (116 liters), and a barrel of petroleum is defined as 42 U.S. gallons (159 liters). Various liquid measures containing from 31 to 42 U.S. gallons (119 to 159 liters) are commonly called barrels, however. A barrel of beer in the United Kingdom is defined as 36 imperial gallons (164 liters). See also Weights and Measures.(edited by Yoshil)

Length

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Length is the measurement of the distance from a given point A to a given point B.Length is usually measured using a basic ruler. A ruler is marked in both customary and SI units. You will use the SI units for all experimentation because in science, the SI system is the standard system of measurement. If what you are measuring is very small, then you will use the millimeter units. The millimeter is one thousandth of a meter (.001 meter).
If the object is a small, but not tiny size than the centimeter is the standard unit of measurement. A centimeter is one hundredth of a meter (.01 meter).

If what you are measuring is more that 100cm (1 meter) than a meter stick is the standard tool of measurement.

Mass

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Mass is the amount of matter that makes up the object being measured. Mass is measured using a balance or scale. There are several types of balances that all measure mass in different ways. A manual balance or scale uses known masses or weights called "mass standards" to determine the mass of the object on the other side. To use a manual balance, the following steps must be observed while using a manual balance.

Manual Balances

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  1. Setup the balance
  2. Use the balancing rider/mass to bring the pans to an even status
  3. Place the object to be measured on the measuring pan.
  4. Begin to place mass standards on the standards pan until the trays even
  5. When the trays are even count the mass standards on the standards tray and record your measurement.


When measuring substances within a container

  1. Before adding the substance to the container measure the mass of the container.
  2. Record the mass of the container
  3. Add the substance to the container
  4. Mass the container with the substance inside it using the above procedure
  5. Record the total mass
  6. Subtract the mass of the container from the total mass
  7. The result of this equation will be the mass of the substance

Electronic Balances

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Electronic Balances use programmed masses as standards for measurements. Electronic balances are also typicaly more accurate then manual ones. Certain procedures must be followed when using electronic balances.


  1. Turn the balance on
  2. Press the button that reads zero or tare (this sets the balance's counter to Zero. Doing this is called "zeroing" the balance)
  3. Add the mass to be measured gently to the balance's tray
  4. Read the measurement on the balance's display
  5. Record the measurement


When measuring substances within a container

  1. Turn the balance on
  2. Zero the balance
  3. Place the container on the balance's tray
  4. Zero the balance again
  5. Add the substance to the container
  6. Read the measurement on the balance's display
  7. Record the measurement

Volume

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Volume is the measurement of the amount of space an object takes up. Volume can be measured in two ways. The method used normally depends on the object to be measured.

Regular Objects

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A regular object is an object whose sides can be measured with a ruler. Various formulas exist to find volumes of these objects.Some of the formulas are as follows where
L=length, W=width, H=height, Ba=Base area, E=edge, R=Radius

  • Cube L*W*H=V or E3
  • Rectangular Prism L*W*H=V
  • Cylinder Ba*H
  • Pyramid 1/3*Ba*H
  • Cone 1/3*Ba*H
  • Sphere 4/3*π*R3

For Additional Formulas See Appendix: Formulae

Irregular Objects

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Irregular objects are anything that does not have flat sides that can be measured with a ruler. The primary method used to measure such objects is called water displacement. In this method, a known amount of water is placed in a container, and the object to be measured is placed into the water. The water will rise within the container. The amount that the water rises by is the volume of the object. The procedure for water displacement measurements is as follows:

 
Figure (d)
  1. Use a Graduated Cylinder or some other marked measuring implement to get a measure of water that will be over the top of the object.
  2. Record the amount of water in the container
  3. Place the object in the container
  4. Measure the level of the water
  5. Subtract the original level of the water from the new level
  6. Record the result

To find the volume of an irregular object you need more than just one tool. You need a graduated cylinder, an overflow can, and some water.

Fill the overflow can with water to the brim and let all the excess water drip out (the water above the nozzle.) Now place the cylinder under the overflow can's nozzle and slowly drop the object into the water. Now read the measurement on the cylinder to find the amount of water that dripped out of the overflow can. That is equal to the object's volume because 1 cubic centimeter =1 milliliter. (edited by Yoshil)


Vocabulary and Questions

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  • length is the distance from a given point A to a given point B
  • Mass is the amount of matter within a given object
  • Volume is the amount of space an object takes up
  • Ruler is a tool that is used to measure small lengths
  • Millimeter is a unit of measurement equal to .001 meters
  • Centimeter is a unit of measurement equal to .01 meters
  • Meter Stick is a measuring tool that is one meter in length
  • Balance is a tool for measuring mass
  • Mass Standards are known amounts of mass used to measure objects on a manual balance
  • Regular Objects are objects that can be measured using simple length measurements and formulas only.

Covering The Reading

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  1. If you have an object that is 90cm long, what is the tool preferred for measuring it?
  2. What type of tool uses mass standards to take measurements?
  3. If an object is 136cm long, what unit is useful for labeling it?
  4. What is the method for taking the volume of irregular objects?
  5. Would you measure the volume of a perfect rectangular prism using water displacement?
  6. What measurement does a balance take?

Critical Thinking

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  1. If you have a cone with Ba=4cm2 and H=7cm what is its volume
  2. When a sphere has volume 535, then what is the measure of the radius?
  3. You drop an irregular object into a graduated cylinder containing 40ml of water, after it enters and the water settles, you read that the water level has risen to 64ml, what is the volume of the irregular object?
  4. If you measure an object using cm what is the maximum number of units you should have?

Exploration

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  1. Use a graduated cylinder to measure some household objects around your house using water displacement.
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