Quantity
|
Name of unit
|
Unit symbol
|
Length
|
metre
|
m
|
Mass
|
kilogram
|
kg
|
Time
|
second
|
s
|
Electric current
|
ampere
|
A
|
Temperature
|
kelvin
|
K
|
12
Scientific notation.
People always search for easy way. That’s why we use acronyms. World wide web is shortened as ”www”, same procedure is applied to long numbers. For instance, speed of light was measured to be approximately 300 000 000 m/s. To write this number we use 12 characters, so to make it easy we write m/s. Now we use fewer characters. This number is now written in “scientific notation”.
100 = 1
101 = 10
102 = 10*10 = 100
103 = 10*10*10 = 1000
108 = 10*10*10*10*10*10*10*10 = 100 000 000
10 -1 =
10 -2 =
10 -3 =
1 = 0.1
10
1 = 0.01
100
1 = 0.001
1000
25 = 2.5*10 1=2.5E1
535 = 5.35*100=5.35*102=5.35E2
0.16 = 1.6*0.1=1.6*10-1=1.6E-1
0.00577 = 5.77*0.001=5.77*10-3=5.77E-3
Symbol
|
Prefix
|
Multiplication Factor
|
E
|
exa
|
1018
|
1,000,000,000,000,000,000
|
P
|
peta
|
1015
|
1,000,000,000,000,000
|
T
|
tera
|
1012
|
1,000,000,000,000
|
G
|
giga
|
109
|
1,000,000,000
|
M
|
mega
|
106
|
1,000,000
|
K
|
kilo
|
103
|
1,000
|
H
|
hecto
|
102
|
100
|
da
|
deka
|
101
|
10
|
d
|
deci
|
10-1
|
0.1
|
c
|
centi
|
10-2
|
0.01
|
m
|
milli
|
10-3
|
0.001
|
|
micro
|
10-6
|
0.000,001
|
n
|
nano
|
10-9
|
0.000,000,001
|
p
|
pico
|
10-12
|
0.000,000,000,001
|
f
|
femto
|
10-15
|
0.000,000,000,000,001
|
a
|
atto
|
10-18
|
0.000,000,000,000,000,001
|
In calculator and computer button EXP is used to write scientific notation.
13
Structure of matter
When you have looked around you at the world, you would have noticed that substances have different properties from each other and that they also have some shared properties.
When you look at a material, you see that material as a whole single object. If you could see all the way down to very tiny sizes, you would notice that an object is really made of much smaller pieces.
You can also notice some other changes in matter. For example, when it is cold outside , the inside of the window becomes misty with tiny water droplets; when cologne is dropped on your hand it disappears in a few second. This makes you think that matter may change in some way. Other changes you will notice are that when wood or coal is burnt it changes to ashes; fruit and vegetables left for a long time become mold.
This shows that matter has different states and that these have their own properties.
You will remember some of the work you have already done on matter last year and learn more about it in this chapter.
In science anything that takes up space and has mass is called.
The volume and mass of matter can be measured. Mass can be measured on an equal arm balance and volume can be measured in different ways depending on the state of the matter.
The structure of particles in each state of a substance
You now that substances are mode of particles called atoms and molecules that are too see. These particles are in a continuous state of motion. The types of motion depend on the state of matter the substance is in.
If you take a piece of stone in your hand you will see that it is either in a symmetric or arbitrary shape and that it is strong when you squeeze it.
When you look at a glass of water you notice it flows easily and take the shape of its container.
When you breathe, air is taken into your lungs and causes your rib cage to increase in volume (expand), when you breathe out the air from your lungs is pushed out and your rib cage goes inwards (contracts).
14
The examples given above show three different states of matter; solid, liquid and gas.
Let’s look at the properties of these three states.
1. The solid state
A piece of stone, a porcelain plate, a metal spoon, a piece of coal; all of these substances have a fixed shape. This is the solid state.
In a solid state the particles are touching one another, so they cannot move/translate from their fixed positions. However, the motion they can make is to vibrate about their fixed positions.
Particles are touching one another
There is almost no space between the particles
Particles cannot change position of translate; they cannot slide over each other.
They have a fixed shape, which doesn’t change whatever container they are placed inside.
It is the most well arranged or ordered state of matter.
It expend when heated.
Достарыңызбен бөлісу: |