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Metric System

# Metric System - Metric System Metric Scientific Scientific...

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Unformatted text preview: Metric System Metric Scientific Scientific Measurements Measurements copyright cmassengale Metric System Metric Developed by the French in the late 1700’s. Based on powers of ten, so it is very easy to use. Used by almost every country in the world, with the notable exception of the USA. Especially used by scientists. Abbreviated SI, which is French for Systeme International. copyright cmassengale Metric Prefixes Metric Regardless of the unit, the entire metric system uses the same prefixes. Common prefixes are: kilo = 1000 centi = 1/100th milli = 1/1000th 1 meter = 100 centimeters= 1000 millimeters copyright cmassengale Length Length Length is the Length distance between two points. two The SI base unit The for length is the meter. meter We use rulers or We meter sticks to find the length of objects. objects. copyright cmassengale Mass Mass Mass is the amount of matter that Mass makes up an object. makes A golf ball and a ping pong ball are the golf same size, but the golf ball has a lot more matter in it. So the golf ball will have more mass. have The SI unit for mass is the gram. The gram A paper clip has a mass of about one paper gram. gram. The mass of an object will not change The unless we add or subtract matter from it. it. copyright cmassengale Measuring Mass Measuring We will use a triple beam balance scale to We triple measure mass. measure Gravity pulls equally on both sides of a Gravity balance scale, so you will get the same mass no matter what planet you are on. no copyright cmassengale Weight Weight Weight is a measure of the force of gravity on an object. Your weight can change depending on the force of gravity. The gravity will change depending on the planet you are on. The SI unit for weight is the Newton (N). The English unit for weight is the pound. copyright cmassengale Gravity Gravity Gravity is the force of attraction between any two objects with mass. The force depends on two things: more distance = less gravity = less weight less distance = more gravity = more weight more mass = more gravity = more weight less mass = less gravity = less weight copyright cmassengale Weight and Mass Weight Jill Earth Moon Jupiter On orbit 1 gravity 2.5 gravities 30kg 0 gravity 750N 0 Newtons mass 30kg 1/6th gravity 30kg weight 300N 50N 30kg Notice that Jill’s mass never changes. Her mother will not allow us to take parts off her, or add parts to her, so her mass stays the same. Jill is 30kg of little girl no matter where she goes! copyright cmassengale Volume Volume Volume is the amount Volume of space contained in an object. an We can find the volume We of box shapes by the formula Volume = length x width x height length In this case the units In would be cubic centimeters (cm3). centimeters So a box 2 cm x 3 cm x So 5cm would have a volume of 30 cm3 volume copyright cmassengale V=LxWxH Base Units Base The base unit for volume is the Liter. We measure volume with a graduated cylinder. copyright cmassengale Graduated Cylinders Graduated Liquids form curved, Liquids upper surfaces when poured into graduated cylinders graduated To correctly read the To volume, read the bottom of the curve called the meniscus meniscus copyright cmassengale Liquid Volume Liquid When the metric system was created, When they decided that 1 cm3 of water they would equal 1 milliliter of water and the 1 mL of water will have a mass of one gram. one 1cm3 water =1 ml of water = 1 gram water copyright cmassengale Water Displacement Water We can use water We displacement to find the displacement volume of objects that are not boxed shaped. are We can put water in a We graduated cylinder. If a rock causes the level to rise from 7 to 9 ml, the the rock must have a volume of 2-mL. volume copyright cmassengale Water Mass and Volume Water 1 cm3 water = 1 mL of water = 1 gram So what would be the mass of 50 mL of water be? 50 grams So what would be the mass of 1 liter of water be? 1 L = 1000 mL so its mass would be 1000 1000 grams or a kilogram. 1000 copyright cmassengale Density Density Density is the amount of matter (mass) compared to the amount of space (volume) compared the object occupies. the We will measure mass in grams and We volume in ml or cm3 volume copyright cmassengale Density Formula Density Density is mass divided by volume. Density = mass/volume Remember, all fractions are division problems. Since the unit for mass is grams, and the unit for volume is ml or cm3, then the unit for density is g/ml, or g/ cm3 copyright cmassengale Density Formula Wheel Density Formula wheels make it Formula easy to solve density problems. problems. Cover the property you Cover are trying to find, and do what is left over. do To find density, cover To the word density. You have mass over volume remaining. So divide mass by volume to find density! density! copyright cmassengale Mass density volume Density Formula Wheel Density To find mass, you cover To the word mass. You now have density times volume remaining. volume To find volume, cover To volume. You have mass over density remaining, so divide mass by density to find volume. volume copyright cmassengale Mass density volume Understanding Density Understanding In the following illustrations, each will represent 1 cm3. Each g will represent 1 gram. Mass = 24g Volume = 8 cm3 Density = 3g/cm3 g g g g g g g g g g g g g g g g g g g g g g g g copyright cmassengale g g g g g g g g g g g g g g g g g g g g g g g g g g •In other words, there are 3 grams in every cm3. copyright cmassengale Density Problem 2 Density g g g g g g g g g g g g •Mass = 12 grams •Volume = 6 cm3 •Density = 2 g/cm3 •In English we say the density of the object is 2 grams in every cubic centimeter. copyright cmassengale Density Problem 3 Density g g g g g g g g g g g g g g g g •Our previous problems were materials of uniform density. They were the same stuff throughout. But many materials are not. Gravel is a great example. •Mass = 16 grams •Volume = 8 mL •Density = 2 g/mL copyright cmassengale Water and Density Water Since 1-gram of water has a volume of Since 1-mL, then the density of water will always be 1 gram/ml. always 5o­mL of water will have a mass of 50 grams, so again the density of pure water will be 1 g/ml. A kg of water will have a volume of 1000­mL, so it’s density will be 1 gram/ml. copyright cmassengale Floating and Sinking Floating Less dense Less materials will float on top of more dense materials. dense Objects with a Objects density of less than 1-g/mL will float on top of water. top Objects with a Objects density greater than 1 g/mL will sink in water. water. copyright cmassengale Neutral Buoyancy Neutral Objects with a density equal to the density of water will float in mid water, at what ever level you place the object. Fish and submarines control their depth by changing their density. copyright cmassengale Objects that Sink! Objects Objects with a Objects density greater than 1 g/mL will sink in water. sink copyright cmassengale Titanic Sails the Ocean Blue Titanic The Titanic is sailing on The its maiden voyage. its What is the density of What this enormous, steel hulled ship, full of machinery, coal, people, and all sorts of heavy things? heavy It’s floating, so it’s It’s density must be less than 1 g/mL. than How can this be? The Titanic is a hollow The vessel full of air! vessel copyright cmassengale Titanic verses Iceberg Titanic After HMS Titanic After struck the iceberg, she started to fill with water. started What happened to her What density? density? As she took on more As and more water, her and her density got closer and closer to 1 g/mL. closer The denser the ship The became, the lower she settled into the water. settled copyright cmassengale Wreck of the Titanic Wreck What is the density What of the Titanic resting on the ocean floor? on Must be greater than Must 1 g/mL, as her steel hull is full of water instead of air. instead copyright cmassengale Comparing Densities Comparing •Where is Where the most dense object? object? •Where is Where the least dense object? object? copyright cmassengale Density Review Density We don’t actually count g’s to find the mass of objects. How would you find the mass of a rock? Use a balance scale. In real life, how would you find the volume of a rock? Use a graduated cylinder and see how much water the rock displaces. copyright cmassengale copyright cmassengale ...
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