Download ppt - Measurement & Conversions

Measurement & Conversions

Measurement in SIMeasurement in SI

• SI (System International)– Used by scientists

throughout the world to communicate results.

– Metric system

– Uses multiples of 10

SI Base UnitsQuantity Unit Used in SI

(symbol)Length or distance

meter (m)

Volume or capacity

liter (L)

Mass gram (g)

Density gram per cubic centimeter (g/cm3)

Time second (s)

Temperature degrees Celsius (°C)

Common SI Prefixes

Prefix Meaning Symbol Example

kilo- 1,000 k km

hecto- 100 h hm

deka- 10 da dam

(none) 1 m

deci- 0.1 d dm

centi- 0.01 c cm

milli- 0.001 m mm

LengthLength

• Meter (m)• Practice

– Larger lines on the metric ruler in the picture show centimeter divisions

– Smaller, unnumbered lines show millimeter divisions.

• How many centimeters long is the shell?

• How many millimeters long is it?

Common Conversions

1 km = 1,000 m

1 m = 100 cm

1 m = 1,000 mm

1 cm = 10 mm

Liquid VolumeLiquid Volume

• Volume– Amount of space that a liquid

takes up.• Liter (L)• Practice

– Graduated cylinders (see picture) measure in milliliters (mL).

– Notice that the water in the cylinder has a curved surface (meniscus).

– To measure the volume, you must read the level at the bottom of the meniscus.

– What is the volume of water in this graduated cylinder?

Common Conversions

1 L = 1,000 mL

MassMass

• Amount of matter in an object

• Gram (g)– Approx. 1 paperclip

• Practice– What is the mass of the

apple?– Suppose a recipe for

applesauce called for one kilogram of apples. About how many apples would you need?

Common Conversions

1 kg = 1,000 g

TemperatureTemperature

• Celsius scale used

• TCelsius = (5/9) X (TFahr- 32)

• Water freezes at 0°C• Water boils at 100°C

Converting Between Units in SIConverting Between Units in SI

• Simply move the decimal point

• 2 Questions to Ask– In which direction did I move the decimal

point?– How many places did I move the decimal

point?

Steps to ConvertSteps to Convert

Kings (kilo) kill humans, Humans(hecto) kill Dragons (deka), BASE (meters, liters, grams), Dogs(deci) eat cats, Cats(centi) eat Mice(milli)"

Example: 12.9 cm = _____ m

• Place finger on what is given (Ex. cm).

• Count # of places you move to get to the unit that is wanted while moving finger. (Ex. 2 left to get to m)

• Move decimal over that many places in the same direction that you moved your finger. (Ex. Move decimal over to the left 2 spaces)

Example: 12.9 cm = 0.129_ m

Converting SI UnitsFurther Practice

Converting SI UnitsFurther Practice

• 4.8 kg = ______ mg

• 6.3 cm = _____ mm

• 12 L = _______KL

Conversion PracticeConversion Practice

Convert between the following units:

1. 600 millimeters =_?_meters

2. 0.35 liters =_?_milliliters

3. 1,050 grams = _?_ kilograms

4. 250 millimeters = _?_ meters

5. 1.5 liters = _?_ milliliters

6. 750 grams = _?_ kilogramsNote: See Edhelper wkshts for further practice

Metric System SummaryMetric System Summary

• Metric (SI) units are used almost entirely throughout science and will be used in this course!

• Length—units are meters• Volume—units are liters• Mass—grams• Prefixes in order of largest to smallest

(k) (h) (da) (d) (c) (m)

kilo hecto deca Base deci centi milli

1000 100 10 [meter] 0.1 0.01 0.001

[liter]

[gram]

Scientific NotationScientific Notation

• Purpose– To make it easier to work with very large or

very small numbers

• Rules– Form: # x 10exponent

– # must be 1 or greater and less than 10– Exponents show how many places the

decimal would have to be moved to get the decimal point directly behind the number.

Steps to Scientific NotationSteps to Scientific Notation

Examples (Larger than 1)4,000 = 4.0 x 103 (this means 4 times 103, or 4 X 1000)

Example (Small than 1)0.0001 = 1 x 10-4

Steps1. Identify where the decimal is currently located. Put your

pen on it.2. Move the decimal so that it is directly behind the number

(between 1 and 10). Count how many spaces over you moved while moving.

3. Put the number in correct scientific notation. # x 10exponent

• If you moved the decimal to the left 3 spaces, then the exponent will be a +3.

• If you moved the decimal to the right 3 spaces, then the exponent will be a -3.

4. General Rule: Decimal moved left: exponent up Decimal moved right: exponent

down


Examples (Larger than 1)1. 4,000 = 4.0 x 103 (this means 4 times 103, or 4

X 1000)

2. 36,000 = 3.6 x 104

3. 2,390,000,000 =

4. 1 = 1 x 100 10 = 1 x 101 100 = 1 x 102

Examples (Smaller than 1)1. 0.0001 = 1 x 10-4

2. 0.00000036 =

3. 0.000000000000287 =


Converting numbers to scientific notation which already have a form similar to scientific notation.

1. 12.6 x 102 = 1.26 x 103

2. 1333.8 x 104 = 1.3338 x 107

3. 0.00023 x 108 = 4. 0.0006 x 1013 = 5. 122.8 x 10-8 =6. 0.003 x 10-5 =

Decimal left, exponent up. Decimal right, exponent down.Remember if a negative number gets smaller, it goes

from -5 to -8 and vise versa.


Examples (Backward conversion)• If exponent is -, move that many places

to the left to make it smaller. • If exponent is + , move that many

places to the right to make it bigger.1. 3.6 x 10-4 = 0.000362. 4.22 x 106 = 4,220,0003. 8.6 x 108 = 4. 7.876 x 10-8 =