Unit-5 Solids, Liquids and Gases (PowerPoint)

8/3/2019 Unit-5 Solids, Liquids and Gases (PowerPoint)

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Density

Remember that density is the mass of onecubic centimetre (or cubic metre) of a

substance.

So for example, gold has a density of19.3

g/cm3

. This means one cubic centimetre(cm3) of gold has a mass of 19.3 grams (orone cubic metre of gold has a mass of19300 kg)


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Density (g/cm3) = mass(g)

volume(cm3)

Or using the formula triangle:

m

D x V

kg/m3

kg

m3

Can you

copy this

please!


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Density of regular shapes

volume = length x width x height

density = mass/volume

mass using a scale

length

width

height

http://www.youtube.com/watch?gl=IE&feature=related&hl=en-

GB&v=14nahP_FVnM


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Precision and Accuracy

PreciseHigh number of significent

figures. Repeated measurements are similar

AccurateNear to the real value

Can you copythis please?
http://images.starpulse.com/Photos/Thumbs/Dexters-Lab-tv-01.jpg


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Density of liquids

Mass of liquid and

cylinder

Mass of cylinder

Mass of liquid

Density = mass/volume

Volume


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Density of irregular shapes (1)

Difference in

level gives the

volume of the

shape mass



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Density of irregular shapes (2)

Displacement can

volume of object

mass



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Pressure

Pressure = Force

AreaN/m2 or Pa

N

m2

F

AP x

Can youcopy this

please?


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An example

A woman of weight 600N has a total shoe area of 150 cm2

and a man of weight 750 N has a total shoe area of 360

cm

2

. What is the pressure beneath their feet?

Angelina pressure = force/area = 600/150 = 4 N/cm2

Brad pressure = force/area = 750/360 = 2.1 N/cm2


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The pressure acts in all directions

Copy!


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Pressure and depth

Pressure increases with

depth (P = gh)

The pressure acts in all

directions


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Pressure difference between

top and bottom

= gh

= 1000 kg/m3x9.8x0.2

= 1960 N/m

2

0.2

m


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Draw these sentences!1. The particles in a solid are close packed.

2. The particles in a solid are in regular positions

vibrating around a fixed point.

3. The particles in a liquid are also close packed.

4. The particles in a liquid also vibrate and move

around randomly.

5. The particles in a gas are far apart.

6. The particles in a gas are moving very quickly.

7. For the same substance (e.g. water), the particles are the same size

in the solid, liquid or gaseous forms.

8. Mr Porter is the worlds best science teacher.


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Solids

Fixed shape

Cannot flow

Difficult to compress

Generally dense


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Liquids

Shape can change

Can flow

Not easy to compress

Generally dense


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Gases

Shape can change

Can flow

Easy to compress

Low density


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Changes of state

.


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Brownian motionFat droplets in milk

.

Einstein's Explanation ofBrownian Motion http://www.practicalph

Brownian

Motion
http://galileoandeinstein.physics.virginia.edu/more_stuff/Applets/brownian/brownian.htmlhttp://galileoandeinstein.physics.virginia.edu/more_stuff/Applets/brownian/brownian.htmlhttp://www.practicalphysics.org/fileLibrary/wmv/brownian_motion.wmvhttp://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=24http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=24http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=24http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=24http://www.practicalphysics.org/fileLibrary/wmv/brownian_motion.wmvhttp://www.practicalphysics.org/fileLibrary/wmv/brownian_motion.wmvhttp://galileoandeinstein.physics.virginia.edu/more_stuff/Applets/brownian/brownian.htmlhttp://galileoandeinstein.physics.virginia.edu/more_stuff/Applets/brownian/brownian.html


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.

Brownian motion is the seemingly random

movement of particles suspended in a fluid

(i.e. a liquid or gas). It is due to theinstantaneous imbalance in the combined

forces exerted by collisions of the particle

with the much smaller liquid moleculessurrounding it.


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Pressure in a gas

Collisions of the gas particles with the side

of a container give rise to a force, which

averaged of billions of collisions per secondmacroscopically is measured as the pressure

of the gas


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PHET!

http://phet.colorado.edu/en/simulation/gas-

properties
http://phet.colorado.edu/sims/ideal-gas/gas-properties_en.jnlphttp://phet.colorado.edu/sims/ideal-gas/gas-properties_en.jnlphttp://phet.colorado.edu/sims/ideal-gas/gas-properties_en.jnlphttp://phet.colorado.edu/sims/ideal-gas/gas-properties_en.jnlphttp://phet.colorado.edu/sims/ideal-gas/gas-properties_en.jnlp


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Pressure versus temperature (at

constant volume)

.


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P/T = constant

P1/T1 = P2/T2

The temperature

MUST be in kelvin

This is only true for a constant

mass of gas at constant volume.


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At -273C, P = 0!!

.


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.


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Absolute/Kelvin temperature and

Celsius

T (in Kelvin) = T (in degrees Celcius) + 273


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Kelvin Temperature

The kelvin Temperature is proportional to

the average kinetic energy of the particles in

a substance.

Note that they are

not all travellingat the same

speed.


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Temperature

The hotter the temperature, the faster the

average speed of the particles

Note that they are

not all travellingat the same

speed.


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pV = constant

p1V1 = p2V2 (at constant temp)

This is only true for a

constant mass of gas

at constant

temperature.

Unit-5 Solids, Liquids and Gases (PowerPoint)

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