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

• 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:

– 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)

1000 100 10 1 0.1 0.01 0.001

Kilogram hectogram decagram Unit(gram)

decigram centigram milligram

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 100 10 1 0.1 0.01 0.001

kilogram hectogram decagram Units(grams)

decigram centigram 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.

• 1 kilogram = 1000 grams

kilogram hectogram decagram gram decigram centigram milligram1 0 0 0

Decimal Point

Start End

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.

• 1 milligram = 0.001 grams

kilogram hectogram decagram gram decigram centigram milligram

100

Decimal PointStartEnd

Convert the following measurements

• 8 grams to centigrams _________

• 6.568 kilograms to grams _________

• 2 grams to milligrams _________

• 9.85 centigrams to grams _________

• 4 decigrams to grams _________

• 5 milligrams to decigrams _________

800 cg

6568 g

2000 mg

0.0985 g

0.05 dg

0.4 g

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?

_______ + ______ + _______ = ________ g300 70 3.4 373.4

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

Mass of beaker without liquid- = Mass of the

Liquid

10 grams 3 grams 7 grams- =

Find the mass of the following objects on your desk

• Washer __________

• Small Density Cube __________

• Two Large Paper Clips__________

• 50 ml beaker (empty) __________

• 20 ml of water __________

5.97 g

5.20 g

3 g

29.10 g

18.79 g