Physics. Willis E. Tower
Metric Table of Mass (or Weight)
The masses commonly used are the milligram, gram and kilogram.
Notice in these tables the similarity to 10 mills equal 1 cent, 10 cents equal 1 dime, 10 dimes equal 1 dollar, in the table of United States money.
Other tables in the metric system are built upon the same plan. Learn the prefixes in order thus: milli, centi, deci, deka, hecto, kilo, myria. The first three prefixes are Latin numerals and represent divisions of the unit. The last four are Greek numerals and represent multiples. In these tables, milli means 1/1000, centi means 1/100, deci means 1/10, deka means 10, hecto, 100, kilo, 1000, myria, 10,000. Two other prefixes are sometimes used, micro which means 1/1,000,000; as microfarad or microvolt, and meg which means 1,000,000, as megohm meaning 1,000,000 ohms.
13. Advantages of the Metric System.—First, it is a decimal system; second, the same form and prefixes are used in every table; third, the standards of length (meter), volume (liter), and mass (kilogram) bear a simple relation to one another. This simple relation between the three standard units may be given thus: first, the liter is a cubic decimeter, and second, the kilogram is the mass of a liter of water. (See Fig. 5) Since the liter is a cubic decimeter, the length of one side is 10 cm. The liter therefore holds 1000 ccm. (10 × 10 × 10). Therefore, 1 liter = 1 cu. dm. = 1000 ccm. and since 1 liter of water has a mass of 1 kg. or 1000 g., then 1000 ccm. of water has a mass of 1000 g., or 1 ccm. of water has a mass of 1 g.
The following table of equivalents gives the relation between the most common English and metric units. Those marked (*) should be memorized.
| (*) 1 meter | = 39.37 inches. | 1 cu, in. | = 16.387 ccm. |
| (*) 1 inch | = 2.54 cm. | 1 cu. ft. | = 28315 cm. |
| 1 foot | = 30.48 cm. | 1 cu. m. | = 1.308 cu. yd. |
| 1 mile | = 1.609 km. | (*) 1 liter | = 1.057 qt. |
| 1 sq. in. | = 6.45 sq. cm. | (*) 1 kg. | = 2.204 lbs. |
| 1 sq. cm. | = 0.155 sq. in. | 1 g. | = 15.44 grains. |
| 1 sq. m. | = 1.196 sq. yd. | 1 lb. | = 0.4536 kg. |
| 1 acre | = 0.405 ha. | 1 oz. | = 28.35 g. |
| 1 hectare | = 2.45 acres. | 1 g. | = 0.0353 oz. |
The c. g. s. system. Scientists have devised a plan for expressing any measurement in terms of what are called the three fundamental units of length, mass, and time. The units used are the centimeter, the gram and the second. Whenever a measurement has been reduced to its equivalent in terms of these units, it is said to be expressed in C.G.S. units.
Important Topics
1. The metric system; how originated.
2. Units; meter, liter, kilogram.
3. Metric tables.
4. Advantages of the metric system.
5. Equivalents.
6. The C.G.S. system.
Exercises
1. Which is cheaper, milk at 8 cents a quart or 8 cents a liter? Why?
2. Which is more expensive, cloth at $1.00 a yard or at $1.00 a meter? Why?
3. Which is a better bargain, sugar at 5 cents a pound or 11 cents a kilogram? Why?
4. Express in centimeters the height of a boy 5 ft. 6 in. tall.
5. What is the length of this page in centimeters? In inches?
6. What is the mass of a liter of water? Of 500 ccm.? Of 1 ccm.?
7. From Chicago to New York is 940 miles. Express in kilometers.
8. A 10-gallon can of milk contains how many liters?
9. What will 100 meters of cloth cost at 10 cents a yard?
10. What will 4 kg. of beef cost at 15 cents a pound?
11. What will 5–½ lbs. of mutton cost at 40 cents a kilogram?
12. How can you change the state of a body? Give three methods.
13. Correct the statement 1 ccm. = 1 g.
14. How many liters in 32 quarts?
CHAPTER II
MOLECULAR FORCES AND MOTIONS
(1) Evidences of Molecular Motion in Gases
14. Size of Molecules.—The difference between solids, liquids, and gases has been explained as due to the different behavior of molecules in the three states of matter. That is, in solids they cling together, in liquids they move freely, and in gases they separate. At this time