Chapter 2 Physical Science Review “Physical Science Methods” Mrs. Nell

Standards of Measurement In order for a measurement to be useful, a measurement standard must be used. A standard is an exact quantity that people agree to use for comparison. Charlemagne Early measurements were based upon parts of the human body. A foot was the length of King Charlemagne's foot. An inch was the distance between knuckles on King Edgar's index finger. A yard was the distance between King Henry the First's nose and thumb.

Measurement Systems The United States still uses the English System of Measurement primarily. Most other nations use a system of measurement based on multiples of ten.

The English System Teaspoons and tablespoons inches

The Metric System The metric system, which was developed in the late 1700s, was the first system of measurement based on multiples of ten. kilo- hecto- deka- UNITS Deci- Centi- Milli- km hm dam meters dm cm mm kg hg dag grams dg cg mg kL hL daL Liters dL cL mL

International System of Units In 1960, an improved version of the metric system was introduced. The International System of Units (abbreviated SI ) is the standard system of measurement used worldwide. Prefix Symbol Multiplying Factor kilo- k 1000 deci- d 0.1 centi- c 0.01 milli- m 0.001 micro- µ 0.000 001 nano- n 0.000 000 001

Using SI Units There are seven base units for measurement in SI. All other SI units can be derived from these seven base units. Quantity Measured Unit Symbol Length Meter m Mass Kilogram kg Time Second s Electric current Ampere A Temperature Kelvin K Amount of substance Mole mol Intensity of light Candela cd

Length The SI base unit of length is the meter (m). The distance from the floor to the door knob is about 1 m. There are 100 centimeters in a meter. A paperclip is about 1 cm wide. There are 10 decimeters in a meter. A crayon is about 1 dm long. A kilometer equals 1000 meters. The length of six city blocks is about 1 km long. There are 1000 millimeters in a meter. The edge of a dime is about 1 mm.

Volume Volume is the amount of space occupied by an object. Volume is measured in cubic units (ex- cm3). V = L x W x H 1 dm3 = 1 liter 1 dm3 = 1000 cm3 1 mL = 1 cm3 *Measurements found by combining other SI units (like volume… which combines SI units of length) are called derived units.

Mass Mass is a measurement of the matter in an object. The SI unit of mass is the kilogram (kg). Grams (g) or milligrams (mg) may be used for measuring objects of small mass. 1 kg = 2.2 lbs One paperclip is about 1 g A nickel is about 5 g

Density Density is the mass per unit volume of a material. Density is a derived unit. To find the density of an object you must divide its mass by its volume.

Density of Some Materials The density of water is important because engineers and scientists use it when they want to know if a material will float or sink. This is known as buoyancy. The rule is if the piece of material weighs less than the same volume of water it will float. If it weighs more it will sink. Material Density in kg/m3 Gold 19,300 Lead 11,300 Silver 10,500 Steel 7,850 Aluminum 2,800 Glass 2,700 Concrete 2,400 Brick 1,400 Rubber 1,100 *Water 1,000 Plastic 910 Paper 780 Pine 450 Balsa Wood 160

Time Time is the interval between two events. The SI unit for time is the second (s).

*No degree symbol is written when using the Kelvin scale. Temperature The Temperature of a material is measured with a thermometer. For most scientific work, temperature is measured with the Celsius scale. On the Celsius scale water freezes at 0 degrees and boils at 100 degrees. The SI unit of temperature is the kelvin (K). Zero on the Kelvin scale (0 K) is the coldest possible temperature (absolute zero). The Kelvin temperature can be found by adding 273 to the Celsius reading. *No degree symbol is written when using the Kelvin scale.

Do you know SI??? Now go study!!!