Unit 2: The Metric System

Metric System Background The Metric, or Imperial, measurement system is very concrete and easy system to use. This system is used around the world, and in so is also called the International System of Units (or SI units) Why would we want to have an international system….? Easy communication!!!

Well, almost everybody… -Burma, Liberia, and the United States are the only countries who do NOT use SI. -Instead, these countries use the Customary System -The Customary System requires you to remember random numbers….1ft =12in, 16oz = 1lb, 5,280ft = 1 mi. -There is no pattern to follow

Remembering the Metric System However, with the Metric System you only need to know prefixes and their values. (See “Metric Prefix Values” slide, it’s the final slide.) Additionally, since SI is based on the power of 10, all you have to do is move the decimal point.

METRIC MEASUREMENTS 1. Length * measured distance from 1 end to another - metric unit is a meter(m) - rulers/metersticks are used in science class to measure length

METRIC MEASUREMENTS 2. Mass *defined as the amount of matter in an object - metric unit for mass is a gram (g) - A triple beam balance, digital scale, and spring scale are all used in measuring an objects mass.

METRIC MEASUREMENTS 3. Volume (liquids) *defined as the amount of space occupied by an object - the metric unit for liquid volume is a liter (l) - a graduated cylinder is used to find the volume of liquids - the term “graduated” means measured

METRIC MEASUREMENTS 4. Density *defined as the amount of mass per unit of volume - formula for density = mass / volume or… D = M / V - units are expressed as a mass unit over a volume unit ex: g / cm³

METRIC MEASUREMENTS - every substance has it’s own density 1. fresh water = 1.0 g/cm³ 2. cork = .24 g/cm³ 3. iron = 7.9 g/cm³ - an object’s density also determines whether it will float or sink.

METRIC MEASUREMENTS 5. Temperature * defined as the amount of kinetic energy in a substance - **everything that moves gives off heat** - thermometers are used to measure temp.

METRIC MEASUREMENTS - there are 3 temp. scales 1. Fahrenheit = (F) Customary system 2. Celsius = (C) Metric system 3. Kelvin = (K) Metric system * Kelvin is used to measure supercold items

Super, super, super cold - The coldest possible temperature is called… Absolute Zero = 0k or -273 degrees C - Why is this the coldest possible temperature…what happens at this temp?? = matter stops moving…so no heat is created, thus no temperature, zero entropy!

Temperature Scales Temp scale Water freezes Water boils F 32 212 C 100 100 K -273C or 0K X

METRIC MEASUREMENTS 6. Time * amount of space between 2 events - metric unit is a second (s) - measure with a clock or stopwatch …Time isn’t exclusive to the metric system, we use the same time units

METRIC MEASUREMENTS Measuring something really small, or something really big we use… Scientific Notation –a short hand way of writing a lengthy number Small measurements us a negative exponent 1 x 10⁻¹² Large measurements us a positive exponent (no sign in front of exponent) 1 x 10¹³

Metric Prefix Values No matter the measurement the prefixes are the same! Conversions are easy…use the staircase to help you! Prefix Name Value Larger Smaller Kilo (k) 1,000 Hecto (h) 100 Deka (da) 10 BASE UNIT 1 Deci (d) .10 Centi (c) .01 Milli (m) .001