Standards of Measurement

Units and Standards

A standard is an exact quantity that people agree to use for comparison

If different measurements are made using the same standard we can compare them

Le Systeme Internationale d’Unites

The International System of Units was developed in 1960

We now call this the SI system for short

SI is a set of standards that are universally accepted and used by scientists around the world

Measurement Systems

What is the purpose of a standard?

Measurement Systems

The SI system is based on multiples of 10 Prefixes are used to show which multiple of

10 is being used

Prefix Symbol Multiplying Factor

Kilo- k 1,000

Deci- d 0.1

Centi- c 0.01

Milli- m 0.001

Micro- µ 0.000 001

Nano- n 0.000 000 001

What will we be measuring?

LengthVolumeDensity

TimeTemperature

Length

We use length to measure size and distance

Meter, centimeter, kilometer

Volume

Volume is the amount of space occupied by an object

1ml = 1cm3

Liters, milliliters

Matter

Matter is anything that takes up space Mass is a measurement of the quantity of matter in

an object Grams, kilograms

Density

Density is the mass per unit of volume of an object How much matter is in a given space

g/cm3

Time

The SI unit for time is the Second (s)

60 s = 1 min 3,600 s = 60 min = 1 hr

Temperature

The SI unit for temperature is the kelvin (K) Zero on the kelvin scale (0 K) is the coldest possible

temperature – absolute zero 0 K = -273 ºC

273 ºC below the freezing point of water!!! COLD!

Temperature

The kelvin scale is based on absolute zero (-273 ºC)

Kelvin Celsius Fahrenheit

Freezing point of Water

273 K 0 ºC 32 ºF

Boiling point of Water

373 K 100 ºC 212 ºF

Converting SI units

How do we convert between units?

You have a length of rope that measures 3,075mm. How long is it in centimeters?

Your drive to school is 12.4km. How far is it in meters?

Converting SI units

The speed limit on the Northway is 65mph. Convert 65mph to km/h.

1 mile = 1.61km

Once you have calculated km/h, convert your answer to m/s.

(Write neatly!! This one can be tricky if you lose your place!)