Metric SystemMetric System

Scientific Scientific MeasurementsMeasurements

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 Who uses the metric system?system?

What is another name What is another name for the metric for the metric system?system?

Used by almost every Used by almost every country in the world, with country in the world, with the notable exception of the the notable exception of the USA.USA.

SI, which is French for SI, which is French for Systeme International.Systeme International.

What is a base unit used in the metric system?

What are the What are the prefixes used in prefixes used in the metric system?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, Kilo, Hecto, Deka, Deci Centi, Milli, Deci Centi, Milli,

If I have the unit…..If I have the unit…..Unit Base unit? Prefix? Measuring?

hg Gram hecto mass

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 What is the SI base unit for base unit for length?length?

What tool is used What tool is used to measure to measure length?length?

The distance The distance between two between two points.points.

MeterMeter

Rulers or meter Rulers or meter sticks are used to sticks are used to find the length of find the length of objectsobjects

What is mass?What is mass?

What is the SI What is the SI unit for mass?unit for mass?

The amount of The amount of matter that makes matter that makes up an objectup an object

GramGram

The mass of an The mass of an object will not object will not change unless we change unless we add or subtract add or subtract matter from itmatter from it

What is weight?

What is the SI unit for weight?

A measure of the A measure of the force of gravity on force of gravity on an object.an object.

Your weight can Your weight can change depending change depending on the force of on the force of gravity. gravity. will change will change

depending on the depending on the planet you are on.planet you are on.

Newton (N)Newton (N) The English unit for The English unit for

weight is the poundweight is the pound

Weight and MassWeight and MassJillJill EarthEarth

1 1 gravitygravity

MoonMoon

1/61/6thth gravitygravity

JupiterJupiter

2.5 2.5 gravitigraviti

eses

On orbitOn orbit

0 0 gravitygravity

massmass 30kg30kg 30kg30kg 30kg30kg 30kg30kg

weightweight 300N300N 50N50N 750N750N 0 0 NewtonNewton

ss

Notice that Jill’s mass never changes. Notice that Jill’s mass never changes. Her mother will not allow us to take Her mother will not allow us to take parts off her, or add parts to her, so parts off her, or add parts to her, so

her mass stays the same. Jill is 30kg of her mass stays the same. Jill is 30kg of little girl no matter where she goes!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 Volume is the amount of space amount of space occupied by an occupied by an objectobject

Measure the length, Measure the length, width, and height, width, and height, then multiply the then multiply the three togetherthree together length x width x length x width x

height= (cubic height= (cubic centimeters: cmcentimeters: cm33))

Not an SI unitNot an SI unit

Measure using a Measure using a graduated cylindergraduated cylinder

SI unit- Liter (l)SI unit- Liter (l)

What if an object What if an object is not square or is not square or liquid, how do liquid, how do we find their we find their volume?volume?

WATER WATER DISPLACEMENTDISPLACEMENT

We can put water We can put water in a graduated in a graduated cylinder. If a rock cylinder. If a rock causes the level causes the level to rise from 7 to to rise from 7 to 9ml, the rock 9ml, the rock must have a must have a volume of 2-mL.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 00C = freezing point 1000C = boiling point

mass per unit mass per unit volume of a volume of a material.material.

Divide object’s mass Divide object’s mass by its volumeby its volume Density = Density =

mass/volumemass/volume d=10g/2cmd=10g/2cm33 = 5 = 5

g/cmg/cm33

g/ml (for liquid)g/ml (for liquid) g/ cmg/ cm3 3 (for solid)(for solid) This is a This is a derived unitderived 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!