Standards of Measurement

Standards of MeasurementNot my own Power Point, taken from scienceplanet.wikispaces.com/file/.../(1-2)+Standards+of+measurement.p...

Standard: • Look at this roll of string:

• 150 what? 150 ft? 150 cm? 150 m?• Measurement = Number + Unit• Standard unit: what all people agree on and

understand.

150

System of Measurement

English System• USA• ft, mile, pound…

Meter System• Most of the world.• m, kg, cm, N…• The basis for the SI

International System of Units (International Bureau of Weights & Measurements in Sevres, France)

Both systems are equally accurate.

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Measuring Distance (Length):• Length is the distance between two points.• SI base unit for length is m• We need to use different unites sometimes:

– cm for things like a pencil– Km for long distances like between RAK and Dubai.

• Remember:– 1m = 100 cm– 1Km = 1000 m– 1cm = 10 mm– 1dm = 10 cm

Measuring Volume• Volume: the amount of space occupied by an

object. • You’ll learn how to measure the volume of:1.Regular solids, like a cube. 2.Liquids.3.Irregular solids, like a pencil or a crown.

Ms. Rania Abdelbaqi - IAT/RAK

1. Volume of regular solids:

Ex: a cube

V = l x w x h = 5 cm x 5 cm x 5 cm = 125 cm3

Where cm3 is a volume unit.

2. Volume of liquids:

-By graduated cylinders.-Most common units are 1 mL = 1 cm3 1 L = 1 dm3 - Ex: how many cubic centimeters are in 1.5L? (check your note book for the answer)

3. Volume of irregular solids:These are the things that don’t have regular

sides to measure.

Their volume can be measured by water displacement method. (→ next slide)

1.Read the volume of

water before immersing

the crown in water.

2000 mL2300 mL

2. Read the volume of

water after immersing

the crown in water.

3. The difference in the water volume,

is the volume of the crown. (300 mL)

Measuring Mass• Mass: How much matter in an object.• Units: kg, g, mg, ….• Remember:

1 kg = 1000 g1g = 1000 mg

• Example: how many kilograms are in 6430 mg? (check your copy book for the answer)

• Density: is the mass per unit volume.

Density =

• What is the density of an object having a mass of 10g and a volume of 2 cm3 ?

Density = = 5 g/cm3

The unit of density is g/cm3

Volume

Mass

32

10

cm

g