Metric System Scientific Measurements

Why metric? Don’t we have our own system?? Yes we have our own system but in science we do a lot of measurements and converting between those measurements. The metric system is much easier to convert because ALL the units are based on the powers of 10. Were the English system is random with decimals. Let me show you……..

Why do we need a standard (all use metric) ? What is accuracy? What is precision? So we can compare our measurements and know we mean the same thing Every one uses the same unit How close your measurement is to what a standard value says it should be Repeating the measurement and getting the same value over and over.

Who uses the metric system? Who uses the metric system? What is another name for the metric system? What is another name for the metric system? Used by almost every country in the world, with the notable exception of the USA. Used by almost every country in the world, with the notable exception of the USA. SI, which is French for Systeme International. SI, which is French for Systeme International.

What is a base unit used in the metric system? What are the prefixes used in the metric system? What are the prefixes used in the metric system? A unit used to measure a specific quantity Length- meter Time- second Temperature- Kelvin Mass – Gram Weight – Newton (NOT POUND!!) Volume – Liter Kilo, Hecto, Deka, Deci Centi, Milli,

If I have the unit….. UnitBase unit?Prefix?Measuring? hgGramhectomass cL km kL cg mm dg Dm mL copyright cmassengale

Prefixes i.e. centigram, centimeter or centiliter

What is length? What is length? What is the SI base unit for length? What is the SI base unit for length? What tool is used to measure length? What tool is used to measure length? The distance between two points. The distance between two points. Meter Meter Rulers or meter sticks are used to find the length of objects Rulers or meter sticks are used to find the length of objects

What is mass? What is mass? What is the SI unit for mass? What is the SI unit for mass? The amount of matter that makes up an object The amount of matter that makes up an object Gram Gram The mass of an object will not change unless we add or subtract matter from it The mass of an object will not change unless we add or subtract matter from it

What is weight? What is the SI unit for weight? A measure of the force of gravity on an object. A measure of the force of gravity on an object. Your weight can change depending on the force of gravity. Your weight can change depending on the force of gravity. will change depending on the planet you are on. will change depending on the planet you are on. Newton (N) Newton (N) The English unit for weight is the pound The English unit for weight is the pound

Weight and Mass JillEarth 1 gravity Moon 1/6 th gravity Jupiter 2.5 gravities On orbit 0 gravity mass30kg30kg30kg30kg weight300N50N750N 0 Newtons 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!

What is volume? How is volume determined for a solid? How do you find the volume of a liquid? Volume is the amount of space occupied by an object Volume is the amount of space occupied by an object Measure the length, width, and height, then multiply the three together Measure the length, width, and height, then multiply the three together length x width x height= (cubic centimeters: cm 3 ) length x width x height= (cubic centimeters: cm 3 ) Not an SI unit Not an SI unit Measure using a graduated cylinder Measure using a graduated cylinder SI unit- Liter (l) SI unit- Liter (l)

What if an object is not square or liquid, how do we find their volume? What if an object is not square or liquid, how do we find their volume? WATER DISPLACEMENT WATER DISPLACEMENT We can put water in a graduated cylinder. If a rock causes the level to rise from 7 to 9ml, the rock must have a volume of 2-mL. We can put water in a graduated cylinder. If a rock causes the level to rise from 7 to 9ml, the rock must have a volume of 2-mL.

What is time? What is temperature? The interval between two events SI unit = seconds Measure of how hot or cold something is SI= Kelvin Celsius- a scale base on the freezing & boiling points of water 0 0 C = freezing point C = boiling point

mass per unit volume of a material. mass per unit volume of a material. Divide object’s mass by its volume Divide object’s mass by its volume Density = mass/volume Density = mass/volume d=10g/2cm 3 = 5 g/cm 3 d=10g/2cm 3 = 5 g/cm 3 g/ml (for liquid) g/ml (for liquid) g/ cm 3 (for solid) g/ cm 3 (for solid) This is a derived unit This is a derived unit What is density? How do you find density? What units are used for density?

Important!! What is the most important rule about numbers in science? NO LONELY NUMBERS!!! All numbers should have a unit!