(Correctly called "SI")The metric system is a system of measuring. It has three basic units:

m

the meter for length

kg

the kilogram for mass

s

the second for time

Metric and British Units

One of the principal advantages of the Metric System is its use of only one unit (standard of size) for each parameter (thing that is being measured). The metric units are interrelated in such a way that only five fundamental standards are necessary. These fundamental standards are identified with an * in the tables below.

Parameter:

Metric Unit

British Units

time
duration, delay

second *
s

second, minute
hour, day

frequency

hertz
1/s

cycle per second

length
distance, displacement

meter
1/299 792 458 light sec
m

inch, foot, yard
rod, chain, furlong, mile

velocity, speed
rate of change of position

meter per second
m/s

foot per second
mile per hour, knot

acceleration
rate of change of velocity

meter per second squared
m/s2

foot per second squared

mass
quantity of material

kilogram *
kg

ounce, pound, slug, ton

force
push, pull, or weight

newton
kg m/s2

pound-force

impulse
force times time

newton second
kg m/s

pound-force second

momentum
mass times velocity

kilogram meter per second
kg m/s

pound foot per second

work, energy
force times distance

joule (pronounced "jewel")
= one newton meter
kg m2/s2

foot pound-force

power
rate of doing work

watt
= one joule per second
kg m2/s3

foot pound-force per second
horsepower

area
size of a surface

square meter
m2

square foot, square yard
acre, square mile

pressure
force per unit area

pascal
newton per square meter
kg/m s2

pound-force per square inch

volume, capacity

cubic meter (stere)
m3

pint, quart, gallon
cubic foot, cubic yard

density, heaviness

grams per cubic centimeter
g/cm3

pounds per cubic foot

Definitions of the SI base units

Unit of length

meter

The meter is the length of the path travelled by light in vacuum during a time interval of 1/299 792 458 of a second.

Unit of mass

kilogram

The kilogram is the unit of mass; it is equal to the mass of the international prototype of the kilogram.

Unit of time

second

The second is the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom.

Converting Metric Units

We know that:

This suggests that:

To convert length from a larger unit into a smaller unit, multiply by the relevant power of 10.

To convert length from a smaller unit into a larger unit, divide by the relevant power of 10.

## Metric System of Measurement

(Correctly called "SI")The metric system is asystem of measuring. It has three basic units:meterfor lengthkilogramfor masssecondfor time## Metric and British Units

Parameter:timeduration, delay

second*s

hour, day

frequencyhertz1/s

lengthdistance, displacement

meter1/299 792 458 light sec

m

rod, chain, furlong, mile

velocity, speedrate of change of position

meter per secondm/s

mile per hour, knot

accelerationrate of change of velocity

meter per second squaredm/s2

massquantity of material

kilogram*kg

forcepush, pull, or weight

newtonkg m/s2

impulseforce times time

newton secondkg m/s

momentummass times velocity

kilogram meter per secondkg m/s

work, energyforce times distance

joule(pronounced "jewel")= one newton meter

kg m2/s2

powerrate of doing work

watt= one joule per second

kg m2/s3

horsepower

areasize of a surface

square meterm2

acre, square mile

pressureforce per unit area

pascalnewton per square meter

kg/m s2

volume, capacitycubic meter (stere)m3

cubic foot, cubic yard

density, heavinessgrams per cubic centimeterg/cm3

Definitions of the SI base unitsUnit of lengthmeterUnit of masskilogramUnit of timesecond## Converting Metric Units

We know that:## This suggests that:

You should be able to work confidently with metric units to solve problems in daily life.

Teaching measureshttp://www.teachingmeasures.co.uk/menu.html

Now, do the following exercises:Exercise 1Exercise 2Exercise 3Exercise 4Exercise 5Exercise 6Do the following test:Test 1Test 2Test 3Test 4Now, do the following exercises:Exercise 1Exercise 2Exercise 3Exercise 4Exercise 5Exercise 6Exercise 7Do the following testTest 1Test 2