Physical Science Ch 2

Standard – Exact quantity that people agree to use for comparison Purpose - When all measurements are made with same standard, measurements can be compared Measurement system – English Metric- multiples of 10 International System of Units - 1960

Chapter 2 -Units of measurement and standards -Length -Mass -Time -Temperature -amount of a substance (atoms/molecules) -Electrical current -luminosity -3 types of graphs

Length -The distance between two points SI Base Unit = meter SI is based in powers of ten: -deci- means 1/10 -centi- means 1/100 100 cm = 10 dm = 1 m

Using Math How many centimeters are in 1.98 meters? Problem-Solving Steps: What is known? 1 m = 100 cm When converting from larger units (m) to smaller (cm) you multiply

1.98 m x (100 cm/1 m) = 198 cm

Volume -The amount of space occupied by an object -If length, width, and height are expressed in centimeters, then volume (length x width x height) is expressed in: cm3 “cubic centimeters” -No tool can measure volume, so combine 2 SI Units (refer to p 38)…. -Volume units are derived units; - 1 Liter = 1 cubic decimeter (dm3)

Practice problem w/ Volume How many liters of gasoline are in 538 cm3? What is known 1 cm3 = 1 mL and 1 L = 1000 mL….therefore 1 L = 1000 cm3 When converting from smaller units (cm3) to bigger (dm3), you divide 538/1000 =?

Answer 538 / 1000 = 0.538 L

Mass A measurement of matter in an object SI unit is kilogram (kg). For objects of small mass, grams (g) or milligrams (mg) are used Convert from g to kg, etc.

Density -Like volume, density is a derived unit -Mass per unit volume, or mass/volume (g/mL) -Each material has its own unique density

Temperature The amount of thermal energy (heat) in a substance. **For now, think of temperature as “how hot or cold something is” -Temperature is measured on the Celsius (c) scale -Water at freezing = 0 degrees C; water at boiling = 100 degrees C -SI Unit is Kelvin (K) = NO DEGREE SIGN!!; find Kelvin by adding 273 to the Celsius temperature

homework p. 56 # 1-10, 16-21 DUE THURSDAY!

2.3: Graphs Line Graphs: ‘ -used to show trends or how data changes over time What information is shown here?

Graphs Bar Graphs: Useful for comparing information collected by counting Height corresponds to a number of (y) This bar graph shows…?

Graphs Circle Graphs - How a fixed # is broken into parts (i.e. percentages) The circular pie represents the total (i.e. 100 %) What does this ex show? Percent Energy Stored by Fuels

Importance of graphs A visual display of informationor data Who uses graphs? Businesses Sports, sport agents, coaches Economics Politics Engineering Science and research ???Anyone else???

Homework p. 56 # 13, 14, 22, 23

Slope: y = mx + b Two points, subtract y-y and x-x: m = (y1-y2)/(x1-x2)