***METRICS***

Measurement

• What is measurement?– any standard of comparison, estimation, or

judgment

Why do we measure things?

– To give information

– To compare things quantitatively (if a person had never seen or heard of these animals before, measurements would help that person compare them)

– Length of a crocodile compared to a gecko

– Height of a Basketball player, compared to horse jockey

– Weight of an elephant, compared to mouse

• What kinds of measurements can you take?– Length– Volume– Mass– Temperature

U.S.A

• What kind of scale does the U.S. use?

– U.S. Customary scale• Including inches, feet, miles

The World & The Scientific Community

– Uses the SI Systeme Internationale d’Unites (French), or Metric System

– As early as the 17th century French scientist found it illogical to have so many measurement systems so they developed one universal system.

• It is easy to use because it is in multiples of 10• Today all countries except the United States,

Burma, and Liberia use the metric system

• Why is it important to use only one scale of measurement in science?

– Scientists need to be able to share and compare their work with other scientists easily.

– It makes it less confusing!

Length

• Basic unit of measure = meter

• What would you measure in meters?– 1. How far you throw a softball– 2. A person’s height– 3. Measure height of a room’s wall

Units for metric length

Unit Abbreviation Meaning1.Kilometer Km

1000m2.Hectometer Hm 100m3.Dekameter Dkm 10m4.Meter m 1m5.Decimeter dm .1m6.Centimeter cm .01m7.Millimeter mm .001m

Multiples of Ten

10 Hm = 1 Km

10 Dkm = 1 Hm

10 m = 1 Dkm

10 dm = 1 m

10 cm = 1 dm

10 mm = 1 cm

King

Henry

Died

Making

Dead

Cows

Moo

King Kilometer

Henry Hectometer

Died Dekameter

Making Meter

Dead Decimeter

Cows Centimeter

Moo Millimeter

Let’s Practice!

• Length

• *Measure from the zero mark not the end of the ruler (meter stick)

What is the measurement?

Cm

What is the measurement?

• 263 mm

• 26.3 cm

• 2.63 dm

• 0.263 m

Cm

8 109

What are these measurements in centimeters, and millimeters?

A B C

Cm

One More, On Your Own

8 109

A= 8.2cm, 82mm

Cm

B= 9.9Cm, 99mm

C= 10.5cm, 105mm

Mass, Temperature, and Time

Mass

Basic unit of mass: = gram (g)

Measuring Mass

Using a triple beam balance1. Place object on the pan2. Move rider on the middle beam notch by notch until

the horizontal pointer drops below zero. Move the rider back one notch

3. Move the rider on the back beam notch by notch until the pointer again drops below zero. Move the rider back one notch.

4. Slowly slide the rider along the front beam until the pointer stops at the zero point.

5. The mass of the object is equal to the sum of the readings on the three beams.

Mass vs. Weight

• Mass – the amount of matter an object contains (the amount of stuff)

IT DOES NOT CHANGE

• Weight- force of gravity on an object– Can vary depending on location of object.

• Example:– Your mass is the same on the moon and on the earth.– Your weight is different on the moon as compared to the

earth.• You weigh less on the moon because the force of gravity is

less on the moon.

Units for measuring mass:

Unit Abbreviation Meaning

1. Kilogram Kg 1000g

2. Hectogram Hg 100g

3. Dekagram Dkg 10g

4. Gram g 1g

5. Decigram dg .1g

6. Centigram cg .01g

7. Milligram mg .001g

Temperature

• Unit of measure :

Celsius (C )

• Example: – Water freezes at 0° C

and boils at 100° C

Time

• Time is simply distinguishing which of two events is earlier and which later

• Time is measured in different increments• Years• Months• Days• Hours• Minutes• Seconds

Volume and Density

Volume - The amount of space an object takes up.

Measuring Volume

• Liquids– Unit of measure = Liters (L)

or (ml)– Use a graduated cylinder– Measure from the bottom of

the meniscus• Meniscus –the curved surface

of a liquid 10

15

20

Measuring Volume

• Regular solids– Unit of measure = cubic centimeter (cm3)– Volume= length x width x height

Or

L x W x H= Volume

• Example– Volume = 20cm x 6cm x 25cm = 3000 cm3

Irregular Solids

• Unit of measure= centimeters cubed (cm3).

• BUT! Measured using ml – ml and cm3 are equivalent units!

• Example: – Volume of a rock using a graduated cylinder

Density

• Density: How much mass in a given volume (How much “stuff” in a certain amount of “space”)

• Formula: Density = mass D = M

volume V

• Example: – A box has a mass of 400 g and a

volume of 15 cm3. What is the density of the box?

• Example: – Bowling ball vs. Beach ball

• Same volume different mass• Which item is more dense?