Transcript Measuring Mass

Measuring Mass
What is Mass?
• Mass is the measure of the amount of matter in
an object.
• Mass and Weight are different. Weight is the
amount of gravitational force pulling on an
object.
• Weight can also change from place to place
(planet to planet), but mass always stays the
same.
Metric Units of Mass Measurement
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Gram (g) – Unit of measurement (starting point)
Milligram (mg) – (1 thousandth of a gram, 0.001, 10-3)
Centigrams (cg) – (1 hundredth of a gram, 0.01, 10-2)
Decigram (dg) – (1 tenth of a gram, 0.1, 10-1)
Decagram (dag) – (ten grams, 10, 101)
Hectogram (hg) – (1 hundred grams, 100, 102)
Kilogram(kg) – (1 thousand grams, 1000, 103)
• The units decigram, decagram and hectogram
are not used as much as the other units.
• Grams are used to measure the mass of
larger things such as candy bars.
• Kilograms are used to measure the mass
of even larger objects like cars.
Metric Conversions
• To convert larger units to smaller ones , you MULTIPLY by units of 10
• To convert smaller units to larger ones you DIVIDE by units of 10
– Example:
1000
100
10
1
0.1
0.01
0.001
Kilogram
hectogram
decagram
Unit
(gram)
decigram
centigram
milligram
– To convert 2 grams to centigrams (1 hundredth of a gram), you multiply by
100:
• 2 x 100 = 200 cg (2 grams = 200 centigrams)
– To convert 3 milligrams (1 thousandth of a gram) to grams, you divide by
1000
• 3 ÷ 1000 = 0.003 g (3 milligrams = 0.003 g)
OR
• Find out how far apart the two prefixes are on the line
above. For example, kilo and hecto are one place apart,
kilo and deca are two places apart, etc.
• Move the decimal point to the left to convert smaller
units or right to convert larger units by the number of
places you found in the previous step. If there is no
decimal in the number, assume it's after the last digit in
the number.
1000
kilogram
100
10
1
0.1
hectogram
decagram
Units
(grams)
decigram
0.01
centigram
0.001
milligram
Example #1
• To convert 1 kilogram to grams (convert larger to
smaller), move the decimal 1 place to the RIGHT and
add zeros where needed for the number of places
you move down the table.
Decimal Point
Start
1
kilogram
0
hectogram
End
0
0
decagram
gram
• 1 kilogram = 1000 grams
decigram
centigram
milligram
Example #2
• To convert 1 milligrams to grams (convert smaller to
larger), move the decimal 1 place to the LEFT and
add zeros where needed for the number of places
you move down the table.
Decimal Point
End
kilogram
hectogram
decagram
gram
• 1 milligram = 0.001 grams
0
decigram
0
centigram
Start
1
milligram
Convert the following measurements
• 8 grams to centigrams
• 6.568 kilograms to grams
• 2 grams to milligrams
800 cg
_________
6568 g
_________
2000 mg
_________
• 9.85 centigrams to grams
0.0985 g
_________
• 4 decigrams to grams
0.4 g
_________
• 5 milligrams to decigrams
0.05 dg
_________
How to Measure Mass
You can use a triple-beam balance or
hanging balance to find the mass of
various objects.
The objects are placed on the pan and
then you move the weights on the beams
until you get the lines on the right-side of
the scale to match up.
Once you have balanced the scale, you add up
the amounts on each beam to find the total
mass.
What would be the mass of the object
measured in the picture?
_______
+ ______
= ________
300
70 + _______
373.4 g
3.4
How to Use a Triple-Beam Balance
1st – Place the object on the pan.
2nd – Slide the large weight to the right until the arm drops below the
line. Move the rider back one groove. Make sure it “locks” into place.
3rd – Repeat this process with the top weight. When
the arm moves below the line, back it up one groove.
4th – Slide the small
weight on the front
beam until the lines
match up.
5th – Add the amounts on each beam to find the total mass to the nearest tenth of a
gram.
How to Use a Hanging Balance
1st – Place the object on the scale.
2nd – Slide the large weight to the right until the arm drops below the
line. Move the rider back one groove. Make sure it “locks” into place.
3rd – Repeat this process with the top weight. When
the arm moves below the line, back it up one groove.
4th – Slide the small
weight on the front
beam until the lines
match up.
5th – Add the amounts on each beam to find the total mass to the nearest tenth of a
gram.
Measuring the Mass of a Liquid
Mass of beaker with
liquid
10 grams
-
Mass of beaker without
liquid
3 grams
=
=
Mass of the
Liquid
7 grams
Find the mass of the following objects
on your desk
5.97 g
• Washer __________
5.20 g
• Small Density Cube __________
• Two Large Paper Clips__________
3g
29.10 g
• 50 ml beaker (empty) __________
• 20 ml of water __________
18.79 g