The person measuring the object needs to put in his mind the right unit of measure should he or she use. An example is a bucket. A bucket has different attributes that can be measured. Some of these attribute are the weight, mass, volume, area (surface area), density, length, etc. This attributes can be measured but there are many units of measure involve in each of the attributes. Standard units of measure are developed so that the confusion between what unit of measure to be used is resolved (Jones, 1998). The following are the standard unit of measure for a certain attribute: Weight Kilograms Mass Kilograms Volume Liters
Area square meters Length meters As said above, measurement is a way of obtaining data. One cannot obtain the right data without the right tool to be used. As with measurement, a right measurement instrument must be used in order to get the right data and in order to estimate with precision and accuracy the object that you want to measure. The following attributes that are stated can be measured with the use of the right measuring instrument. For clarification, weight is not the same as mass. Weight is the amount of mass that is present when it is suspended in a spring scale when acted upon by the earths gravity.
On the other hand, mass is the amount of matter present in an object. Weight is measured with the use of spring scale or a weighing scale. The value of the weight in the earth can be the same as the value of the mass. But once the force acting on the object changes the value of the weight will change and the mass will stay the same. Generally, masses like mass of a person can be obtained by the use of the same instrument used in measuring weight in earth. Volume can be measured by the use of some known instruments like measuring cup for liquid, pipette for liquid, graduated cylinder (for liquid and solid) and pneumatic trough for gases.
Area is measured by the use of a planimeter. Length is usually measured by the use of instruments like ruler, tape measure, meter stick, yard stick etc (Fuchs, 1996). The attributes being measured is deeply related to the unit of measure being used. First, the attributes maybe too large or too small for unit of measure, in that case there are other units of measure given. The hierarchies of units are given in a unit system. There are two unit systems that are popular today. The SI system and the English system give a complete list of all the unit of measures according to the quantity (Abbot, 2003).
Some of the attributes of the bucket can only be obtained by the use of measuring devices. Other attributes, however, can be obtained with the use of some formulas. For example: Volume and area can be obtained by formulas like V = 1/2? r2h, and A = 2? rh + ? r2. The formula for the volume is obtained by the use of the formula for the volume of a cylinder. Bucket is usually cylindrical in shape. The formula for the area is obtained by using the formula of the surface area of an open cylinder. Other formulas can be obtained for the attributes of the bucket. Another example is the density of the bucket.
In general, the density is equal to the mass divided by the volume of the bucket. Since mass can be obtained with the use of a measuring device and volume can be obtained with the use of the given formula then one can solve for the density of the bucket with the general formula (Manura, 2005). Another concept that should be discussed is approximation and estimation. As said earlier, measurements are always an estimate. Approximation and estimation are very important concepts regarding measurements because they will be the basis of the accuracy and precision of a measurement.
One does not get accurate and precise results all the time with the use of measuring devices. There might be errors that can come up from time to time. To properly record results obtained using measuring devices, one must take note of the errors in measurements and put it in the resulting measure to obtain a more precise and accurate result. Results should be written in the form: result + uncertainty. For example, if a buckets height according to a 9 different rulers is 20 centimeters. And another reading from a different ruler is 20. 3 centimeters. Then the resulting measurement should be 20 ± 0. 3 centimeters (Hoult, 2009).
Abbot, D. (2003). Assessing Student Understanding of Measurement and Uncertainty. Retrieved March 20, 2009 from http://www. compadre. org/precollege/items/detail. cfm? ID=4417 Fuchs, H. (1996). The Dynamics of Heat. New York: Springer Hoult, D. (2009). Measurements. Retrieved March 20, 2009 from http://www. saburchill. com/physics/chapters/0065. html Jones, N. (1998). Units of Measurement. Retrieved March 20, 2009 from http://www. sli. unimelb. edu. au/planesurvey/prot/formulae/unit1. html Manura, D. (2005). Areas, Volumes, Surface Areas. Retrieved March 20, 2009 from http://math2. org/math/geometry/areasvols. htm