Chapter 2: Measurement & Problem Solving pg LO: I can use unit conversions successfully in mathematic calculations.

Units of Measurement Two common systems: English & Metric (International System or SI). Common Base Units Meter (m) = length Kilogram (kg) = mass Seconds (s) = time

Metric Prefixes A numerical prefix that changes a number by powers of 10 Examples What is the meaning? Kilometer = Centimeter = Decimal = Scientific Notation Pg. 26 of your text!

Unit Conversions Converting a given unit into a desired unit Examples How many feet (ft.) are in 194 centimeters (cm)? How can we solve this problem?

Unit Conversions Setting up ratios (comparing one unit to another) in order to convert a given unit into a desired unit through multiplication.

Solution Maps A great way to map out a problem so you know what you need to do!

Solution Maps Question: Question: How many feet (ft.) are in 194 centimeters (cm)? How do we get from centimeters (cm)  feet (ft.)?

Example Solution Maps Question: How many laps should you run to run 10.0 kilometers (km)? Note: Important conversion factors are on the PDF “End Paper” tab.

Example Solution Maps Question: How many centimeters (cm) are in 72 miles? Note: Important conversion factors are on the PDF “End Paper” tab.

Unit Conversions Things to Remember Always write every number with its associated unit Identify your starting point (given unit) and devise a solution map towards what you must find (desired unit) Check sig figs last when doing your calculations Determine if your answer makes sense

Practice Ex: How many hours are in 4.5 years?

Practice Ex: Convert 5.89 x 10 7 µg to kg

Unit Conversions What do I do when a unit conversion is raised to a power? You must also raise the conversion factor to that power.

Unit Conversions Question: How many cubic feet (ft 3 ) are in 4102 cubic centimeters (cm 3 )? Solution MapSolution

Density What is Density? A ratio of an objects mass to its volume How is it calculated? Density =_mass_  D = M Volume V Density is… …Thus density can be used as a conversion factor!

Density Ex: Using density as a conversion factor The density of aluminum is 2.70 g/mL. What is the volume in liters of 256 g of an aluminum sample?

Temperature (Kelvin vs. Celsius) Kelvin: SI base unit of temperature. 0 K = Absolute zero  all particles (atoms) no longer have energy (heat). Changing between Kelvin & Celsius temperature Kelvin  Celsius = Kelvin Temp – 273 = Celsius Temp Celsius  Kelvin = Celsius Temp = Kelvin Temp

Lesson Summary Rate your understanding of the lesson (1-4) Think about your learning concerning the following points  What types of math computations were discussed in the chapter and why are they important?  How do solution maps and carrying units help you arrive to a correct answer when doing unit conversions?