Scientific Units 1.2 Notes Part B

Unit Objectives Use appropriate SI units for length, mass, time, temperature, quantity, area, volume and density. (ACT Quality Core I.A.2.b) Use appropriate SI units for length, mass, time, temperature, quantity, area, volume and density. (ACT Quality Core I.A.2.b)

SI Units Le Système International d’Unités (SI) Le Système International d’Unités (SI) International System of Units in USA International System of Units in USA A modern version of the metric system based on a decimal system A modern version of the metric system based on a decimal system Understood throughout the world Understood throughout the world Each type of measurement has a base unit Each type of measurement has a base unit Multiples of 10 Multiples of 10

Length Distance between 2 points Distance between 2 points SI base unit = meter (m). SI base unit = meter (m). Metric rulers and meter sticks are used to measure length Metric rulers and meter sticks are used to measure length

Mass The quantity of matter in an object The quantity of matter in an object SI Base Unit = gram (g) SI Base Unit = gram (g) NOT the same as weight NOT the same as weight Weight = Newton (N) = measure of gravitational force on an object Weight = Newton (N) = measure of gravitational force on an object

Volume The amount of space occupied by an object The amount of space occupied by an object Can measure volume of a solid, liquid, or gas Can measure volume of a solid, liquid, or gas SI base unit is the liter, L SI base unit is the liter, L A liter occupies the same volume as a cubic decimeter, dm3. A liter occupies the same volume as a cubic decimeter, dm3. 1 L = 1 dm3 1 L = 1 dm3 (1 mL = 1 cm3) (1 mL = 1 cm3)

Measuring Volume FOR Solids FOR Solids Measure length, width, and height Measure length, width, and height Multiply the three numbers and their units together (V = l x w x h) Multiply the three numbers and their units together (V = l x w x h) Volume = expressed in cubic centimeters, cm3 Volume = expressed in cubic centimeters, cm3

SI Units Time = second (s) = interval between 2 events Time = second (s) = interval between 2 events Temperature = Kelvin (K) = measure of the average kinetic energy of particles in an object Temperature = Kelvin (K) = measure of the average kinetic energy of particles in an object Kelvin = °C +273 Kelvin = °C +273 °C = Kelvin °C = Kelvin Example: 20 °C = 293 K Example: 20 °C = 293 K

Time Time is the interval between two events. Time is the interval between two events. Or the time it takes for something to happen Or the time it takes for something to happen SI unit for time = second (s) SI unit for time = second (s)

Temperature Measure of how hot or how cold something is. Measure of how hot or how cold something is. For most scientific work, temperature is measured on the Celsius (C) scale. For most scientific work, temperature is measured on the Celsius (C) scale. On this scale, the freezing point of water is 0  C, and the boiling point of water is 100  C. On this scale, the freezing point of water is 0  C, and the boiling point of water is 100  C. Between these points, the scale is divided into 100 equal divisions. Each one represents 1  C. Between these points, the scale is divided into 100 equal divisions. Each one represents 1  C.

Temperature SI Unit = Kelvin (K). SI Unit = Kelvin (K). Absolute Zero (0K) = coldest possible temperature Absolute Zero (0K) = coldest possible temperature Absolute zero is equal to -273  C which is 273  below the freezing point of water. Absolute zero is equal to -273  C which is 273  below the freezing point of water.

Finding Kelvin Kelvin temperature can be found by adding 273 to the Celsius reading. Kelvin temperature can be found by adding 273 to the Celsius reading. On the Kelvin scale, water freezes at 273 K and boils at 373 K. On the Kelvin scale, water freezes at 273 K and boils at 373 K. To find Kelvin simply add 273 to the °C To find Kelvin simply add 273 to the °C K = °C +273 K = °C +273 To find Celsius, subtract 273 from the K To find Celsius, subtract 273 from the K °C = Kelvin °C = Kelvin - 273

Temperature These three thermometers illustrate the scales of temperature between the freezing and boiling points of water. These three thermometers illustrate the scales of temperature between the freezing and boiling points of water.

Density Density is the mass per unit volume of a material Density is the mass per unit volume of a material You find density by dividing an object’s mass by the object’s volume You find density by dividing an object’s mass by the object’s volume

Density = Derived Unit SI Unit = g/cm3 SI Unit = g/cm3 A combination of SI units. A combination of SI units. A unit obtained by combining different SI units or multiply an IS unit by itself = a derived unit. A unit obtained by combining different SI units or multiply an IS unit by itself = a derived unit.

SI Units Length = meters Length = meters Mass = grams Mass = grams Time = seconds Time = seconds Temperature = Kelvin Temperature = Kelvin Volume = Liters, cubic centimeters Volume = Liters, cubic centimeters Density = g/mL, g/cm3 Density = g/mL, g/cm3

In-Class Assignment/Homework Page 879 #1-4, 6-10 Math Problems Page 879 #1-4, 6-10 Math Problems 1 m = 10 dm =100 cm = 1000 mm 1 m = 10 dm =100 cm = 1000 mm 1 dm = 10 cm = 100 mm 1 dm = 10 cm = 100 mm 1 cm = 10 mm 1 cm = 10 mm 1 L = 1 dm 3 1 L = 1 dm 3 1 mL = 1 cm 3 1 mL = 1 cm reinforcement WKT 1.2 reinforcement WKT