measuring small items small objects are measured in cm or mm. how many mm are in 1 cm? 1 cm =...
TRANSCRIPT
MEASURING SMALL ITEMS
Small objects are measured in cm or mm.
How many mm are in 1 cm?
1 cm = _______ mm
When measuring small objects, measure to the nearest mm.
MEASURING METRIC LENGTH
USING A METRIC RULER
Start from 0! Read first to the nearest
cm. The numbers are cm
Read next to the nearest mm The small, numberless lines
are mm.
This red tape is 2.3 cm long
READING A METRIC RULER
LET’S PRACTICE!
Did you say 5.1 cm?
LET’S PRACTICE!
Did you say 7.1 cm?
VOLUME
VOLUME The amount of space an object takes up
CALCULATING VOLUME OF RECTANGULAR SHAPED SOLIDS
Calculate the volume using the formula:
Volume=L x W x H (length x width x height)
Width = depth Make sure you also multiply
the UNITS (cm x cm x cm = cm3 )
UNIT FOR VOLUME OF SOLIDS
objects with small volumes use cm3 (cubic centimeter)
1 cm3 is equal to the volume of a cube that measures 1cm on each side.
Objects with large volumes use m3 (cubic meters)
1 m3 is equal to the volume of a cube that measures 1m on each side.
HOW DO WE FIND THE VOLUME OF THIS?
1. Treat it like 2 rectangles.2. Find the L, W and H for BOTH
rectangles.3. Calculate volume for both
rectangles using L x W x H.4. ADD them together.
Rectangle 1: L = 80 mm, W = 10 mm,, H = 20 mm80 x 10 x 20 = 16 000 mm3
Rectangle 2: L = 20 mm, W = 10 mm, H = 40 mm20 x 10 x 40 = 8 000 mm3
Total Volume8 000 mm3 + 16 000 mm3 = 24 000 mm3
VIDEO INSTRUCTION
Optional Video – Calculating Volume
SIGNIFICANT FIGURES When calculating volume, your FINAL answer can
have no more decimals than your LEAST accurate measurement.
So, YOU MUST ROUND!
If you are measuring to the nearest millimeter, your answer should have ONLY 1 decimal point.
Example: 1.5 cm x 1.5 cm x 1.5 cm = 3.375 cm3 This answer is not possible. If we can only measure with a ruler to the mm place,
the answer CANNOT be beyond the mm place. Therefore, the correct answer would be 3.4 cm3
VOLUME Volume of Liquids
UNIT USED TO MEASURE LIQUID
base unit for liquid is Liter (L)
Small volumes are measured in milliliters (mL)
1000 mL = 1 L(which you should
know from practicing unit conversions!)
MEASURING VOLUME OF A LIQUID
Tool used to find liquid volume is Graduated cylinder.
Rules for Reading a Graduated Cylinders1. Place on flat surface.2. Read from the bottom
of the meniscus.3. Get to eye level with
the level of the liquid.
MENISCUS The curve in the top surface of liquid in the graduated cylinder
CALCULATING VALUE OF LINES ON GRADUATED CYLINDER
Find the difference between the labeled sections.
Divide by number of sections between them.
READING A MENISCUS - PRACTICE
Read the milliliter marking at the bottom of the curve
What is the value of each line on this cylinder?
What is the volume of liquid in this cylinder?
MORE PRACTICE!•Difference between the marked lines• 25-10 = 10 ml
•Number of sections between• 10
•10 / 10 = 1
•Value is 1 mL
HOW TO READ A GRADUATED CYLINDER - VIDEOWhat is the value of each line on these
cylinders?What is the volume of these cylinders?
TICKET OUT Liquid Volume
1. What is the name of the tool used the measure liquid volume?
2. What is the metric base unit for liquid volume?3. What is the base unit for smaller amounts of
liquid?4. What is the volume of the liquid in the cylinders
below?
A
B
C
VOLUME
Volume of Irregular Solids
FINDING THE VOLUME OF AN IRREGULAR SOLID OBJECT
Use the water displacement method
Steps1. Pour water to an even
value in a graduated cylinder.
2. Record amount as V1.
3. Carefully slide the object into the water. Record the volume as V2.
4. V2 - V1 = Volume of Object
HOW DOES THE WATER DISPLACEMENT METHOD WORK?
Video on Displacement
UNIT FOR IRREGULAR OBJECT?
Use cm3 for small irregular shaped objects.
How can something solid be measured in mL?
1 cm3 = 1 mL
LET’S PRACTICE
Find V1 Find V2 V2-V1= ?
MASS Mass is a measure of the amount of matter an object contains.
UNITS OF MASS
The basic unit of mass in the SI system is the kilogram (kg). Best for measuring the mass of
people, cars, or bicycles. For smaller units use grams (g)
Best for measuring mass of small objects like paperclips and cell phones
MEASURING MASS
To find the mass of an object use a triple beam balance. It compares the mass of the
object you are measuring to a known mass.
THE DIFFERENT PARTS OF THE TRIPLE-BEAM BALANCE.
PanRiders
BeamsPointer
USING A TRIPLE BEAM BALANCE
1. Set balance to 0.2. Place the object on the pan3. Shift the riders on the beams
until they balance the mass of the object
1. Start with the large rider (increments of 100)
2. Next, the medium sized rider (increments of 10)
3. Lastly, the small rider (increments of 0.1)
MASS VS. WEIGHT
Weight is a measure of the force of gravity acting on an object. Mass measures the amount of matter an object
contains, it remains constant. W = mass x gravity
Weight can CHANGE.
DENSITY
DENSITY The measure of how much mass is contained in a given volume
WHAT EXACTLY IS DENSITY?
Think about it as how heavy something is for it’s size.
Compare a basketball and a bowling ball. They are the same size but the bowling ball has more mass.
So which has more density?
CALCULATING DENSITY Density = Mass / Volume
( D = m/v )
UNIT FOR DENSITY
Because density is actually made up of two other measurements (mass and volume) an objects density is expressed as a combination of two units
Density of Solids g/cm³ (you say it as grams per
centimeter cubed)
Density of Liquids g/mL (you say it as grams per
milliliter)
DENSITY TRIANGLE
•If you know two of the three measurements in the density triangle, you can solve for the third.
•Cover the measurement you want to solve for and you are given the formula necessary for solving the problem.
•Example: Cover the D and you are left with m/v.
•Cover the M and you are left with D x V. To solve for mass use the formula M = D x V
•Cover the V and you are left with M/D. To solve for volume use the formula V = M/D
DENSITY TRIANGLE
•PRACTICE
•SOLVE for Volume •D = 10 g/mL•M = 100 g
•Solve for Mass•V = 25 mL•D = 100 g/mL
•Solve for Density•V = 10 cm3•M = 150 g
DENSITY “RULES”
Density is a characteristic property of a substance.
All samples of a specific substance will have the same density. It doesn’t matter how big or small the sample is.
Density can be used to identify what a substance is. It is very useful!
Example (find the density): 1 cm3 of gold has a mass of 19.3 g.
2 cm3 piece of gold has a mass of 38.6 g.
Density of common substances Ice- 0.9 g/cm3
Water- 1.0 g/mL Aluminum- 2.7 g/cm3
Gold- 19.3 g/cm3
FIGURE 6: APPLYING CONCEPTS: HOW COULD YOU USE DENSITY TO DETERMINE WHETHER A BAR OF METAL IS PURE GOLD?
If the bar of gold has a density that is greater than or less than 19.3 g/cm³, then the sample is not pure gold.
Densities of Some Common
Substances
Substance
Density(g/cm³)
Air 0.001
Ice 0.9
Water 1.0
Aluminum 2.7
Gold 19.3
FACTORS THAT AFFECT DENSITY
1. Add “something” to a liquid or gas to increase it’s density.
1. Ex. Adding sugar or salt to water
2. Temperature – increase the temperature and the density will decrease.
1. “warm air rises”
3. Changing the pressure.
FLOATING AND SINKING
An object will float if it is less dense than a surrounding liquid.
An object will sink if it is more dense than a surrounding liquid.
The density of water is 1 g/mL. If an object has a density of greater than 1 g/mL
it will sink in water. If an object has a density less than 1 g/mL it will
float in water.