1. DESCRIBE WHAT IT MEANS TO MEASURE When you take a measurement there are certain factors that prevent you from ever getting the exact correct value. For instance on a ruler you can never know the exact length of something because your eyes can only see something so much. This is not to mention that the lines on rulers are not infinitely thin. Therefore, a ruler would be useless in measuring a grain of sand. this too goes for electronic measurements. Often signals retrieved must be digitized, or broken into finite pieces. Since in reality signals are analog this digitization has an inherent uncertainty just like the ruler. Another example would be a stopwatch measuring time. A watch that has increments of minutes is fine for checking how long someone has been away at a lunch break, but in a horse race the uncertainty of 1 minute is far too large. Rather, youd need a watch accurate down to milliseconds. As you can imagine, there are numerous types of uncertainties and a researcher must be aware of the uncertainty values of their equipment so that they are able to determine the worth of their results. 2. DESCRIBE THE DEVELOPMENT OF MEASUREMENT FROM THE PRIMITIVE TO THE PRESENT INTERNATIONAL SYSTEM OF UNITS The smallest unit of ancient measurement was the digit, the width of a finger. Next to the digit was the palm, equal to 4 digits, and the scale continued up to the cubit, equal to 28 digits. For units smaller than a digit, the Egyptia ns were the first to invent fractions. The Egyptians were not able to monopolize the measuring system. The Babylonians also devised measures stemming from a cubit, though 6 mm longer than that of the Egyptians. This cubit was then divided into 30 kus, roughly equal to a digit. The earliest known decimal system is the Harappan system; from 2500 B.C. to 1700 B.C. Evidence suggests that they had two different series of weights. One system was based on a measurement of the Indus inch (1.32 modern inches). Since their system was based on base-10, ten Indus inches equaled 13.2 inches, the measure of a foot. The other scale was discovered in the form of a bronze rod with markings of 0.367 in. 100 units of that would be 36.7 inches, approximately the length of a stride. Measurements of the Harappan ruins show that they used these measurements extremely accurately. European systems of measurement were based on the Roman system. The Romans, in turn, borrowed their measurements from the Greeks, who had based it on the Babylonians and the Egyptians. Their base unit was the breadth of a finger. Unlike the other cultures, they only had three widely used units of measurement: the finger, the foot and the Greek cubit. The Greeks also standardized weight by stabilizing the size of containers to weigh goods and by creating a standard set of measures. The Romans changed the Greek system slightly, by creating the pace, equal to five feet. Thousand paces was a Roman mile, extraordinarily close to the modern British mile. It was in 1672, that Sir Isaac Newton actually made a vital discovery about the “Newton Rings” which actually used light to measure distances. Neither he nor the world at large understood the great implications of it, and today “interferometry“ as it is called helps measure precise distances to within millionths of an inch or a millimeter. The French, on the other hand, used a bewildering array of measures. Standardization was a big problem since no one could come to an agreement. As late as 1788 Arthur Young wrote in Travels during the years 1787, 1788, 1789 published in 1793, “In France the infinite perplexity of the measures exceeds all comprehension. They differ not only in every province, but also in every district and almost every town”. The English though tried to standardize as early as in the 13 th century, by England issuing a royal ordinance “Assize of Weights and Measures” to bring some unity. Wren had proposed a new system based on the yard defined as the length of a pendulum beating at the rate of one second in the Tower of London. Britain and Scotland uniting ensured a better prevalence for the system but it was hard when each province wanted its own system followed. In 1824, the English Parliament legalized the yard th at was first proposed in 1760. 3. CONVERT MEASUREMENTS FROM ONE UNIT TO ANOTHER FOR EACH TYPE OF MEASUREMENTS INCLUDING THE ENGLISH SYSTEM Metric to English English to Metric Length: 1 mm = 0.04 in 1 cm = 0.39 in 1 m = 39.37 in = 3.28 ft 1 m = 1.09 yd 1 km = 0.62 mi Length: 1 in = 2.54 cm 1 ft = 30.48 cm = 0.305 m 1 yd = 0.914 m 1 mi = 1.609 km Weight: 1 g = 0.035 oz 1 l = 1.057 qt Weight: 1 oz = 28.350 g 1 lb = 0.453 kg Capacity: 1 ml = .2 tsp 1 l = 1.057 qt Capacity: 1 tsp = 5 ml 1 c = 236 ml 1 qt = 0.946 l 1 gal = 3.785 l Proportions will help you make conversions when working with measurements. Create a unit conversion ratio, which is always equal to 1: 4. ESTIMATE OR APPROXIMATE THE MEASURES QUANTITIES SUCH AS LENGTH, WEIGHT/MASS, VOLUME/CAPACITY, TIME, ANGLE AND TEMPERATURE (USE OF INSTRUMENTS) Estimating length We can estimate some lengths and distances using approximate values for measurements. For example, one meter is approximately the length from your shoulder to your fingertips, if you stand with your arm outstretched. A meter is also approximately the distance of one large step or jump. Whilst estimating length and distance can be useful, we often need to know exactly how long something is. To measure accurately, we use measuring instruments. Some examples are given in the table below: A ruler is usually has centimeter and millimeter units on it. They are most commonly 15 or 30 cm long. A ruler could be used to measure the length of small tin, or the length of a piece of paper, for example. A measuring tape has centimeter and meter units marked on it. Measuring tapes are useful for measuring lengths of cloth, or large household objects like furniture and rooms. 5. USE APPROPRIATE INSTRUMENTS TO MEASURE QUANTITIES SUCH AS LENGTH, WEIGHT/MASS, VOLUME, TIME, ANGLE, TEMPERATURE; AND Mass Mass is a measure of how heavy something is i.e., it is the amount of matter present in it. It can be determined in the laboratory by using analytical or electrical balances. [weighing scale] • Mass is measured in grams (g), kilograms (kg) and tonnes. These are known as metric units of mass. 1 kg= 1000 g 1 tonne = 1000 kg • Ounces and pounds are old units of mass. These are known as imperial units. MEASURING LENGTH Length is a measure of how long or wide something is. Rulers and tape measures can be used to measure length.[ruler] • Length is measured in millimetres (rom), centimetres (em), metres (m) or kilometres (km). These are known as metric units of length. 1 cm= l0mm 1m= 100cm 1 km= 1000m • Miles, feet and inches are old units of length. These are known as imperial units of length. There are 12 inches in a foot. An inch is roughly equal to 2.5 centimetres. A foot is roughly equal to 30 centimetres. A mile is roughly equal to 1.5 kilometres. MEASURING CAPACITY OR VOLUME Capacity or volume is a measure of how much space something takes up. Measuring spoons or measuring jugs can be used to measure capacity. • Capacity is measured in millilitres (mL) and litres (L). 1L=1000mL • Pints and gallons are old units of capacity (imperial units). There are 8 pints in a gallon. A pint is equal to just over half a litre. A gallon is roughly equal to 4.5 litres. MEASURING TEMPERATURE The thermometer is used to measure temperature. There are three common scales to measure temperature (degree Celsius), °F (degree Fahrenheit) and K (kelvin). Here, K is the SI unit. The thermometers based on these scales are shown in Fig. 2.9. Generally, the thermometer with celsius scale are calibrated from 0° to 100° where these two temperatures are the freezing point and the boiling point of water respectively. The fahrenheit scale is represented between 32° to 212°. The temperatures on two scales are related to each other by the following relationship: OF= 9 /5(OC) + 320 The kelvin scale is related to celsius scale as follows: K = o C + 273.15 It is worthwhile to note that the temperature below 0Oc (i.e., negative values) are possible in celsius scale but in kelvin scale, negative temperature is not possible. 6. SOLVE PROBLEMS INVOLVING FORMULAS IN FINDING PERIMETER, AREA AND VOLUME 1. Jose wants new carpeting for his living room. His living room is an 8 m by 8 m rectangle. How much carpeting does he need to buy to cover his entire living room? ANSWER: Solution you need to find the area for this problem. Area = 8 m × 8 m = 64 m2 64 sq m 2. Tiffany is making a display board for the school play. The display board is a 9 ft by 9 ft rectangle. If ribbon costs $1 per foot, how much will it cost to add a ribbon border around the entire display board? ANSWER: Solution Find the perimeter first and then calculate the cost of the ribbon. Perimeter = 2 × (9 ft + 9 ft) = 36 ft Cost = 36 ft × $1 / ft = $36 $36 [ ASSIGNMENT SAKUNG ANAK ]
Posted on: Tue, 22 Oct 2013 15:45:33 +0000
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