Answers

Here are the answers to the questions as promised. Now correct the work that you blogged. Two options to do this:

1. Send another e-mail to your blog called “Corrections to…” and highlight the changes in a different colour.

2. Edit your blog post and make the changes in a different colour.

Cheers,

Mr B

5.9 and 5.10 answers

28 October 2011

10:21
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5.7 and 5.8 Starter answers

28 October 2011

11:00
· What are the 6 processes shown by the arrows?

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Melting

Boiling

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5.7 and 5.8 Answers

28 October 2011

10:20
· Collins p.112
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1a
· Particles in a solid are strongly bonded to each other so their particles are held in a fixed, regular pattern and can not move
· The bonds between particles in liquids and gases are weaker and therefore their particles can move relative to each other

1b
· The particles in solids and liquids are closely packed and they are therefore incompressible
· The particles in a gas are very widely spaced and the forces between them are very weak so they can spread out to fill their container
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Boiling
· Boiling occurs when you heat a liquid until the average energy of the particles is great enough for them to turn into a gas
· Boiling occurs at a fixed temperature called the boiling point
· Boiling occurs throughout a liquid
· It is a fast process
· [cid:image006.png@01CC9575.884BC100]

Evaporation
· Evaporation occurs when a liquid is left open to the air
· Only particles at the surface of the liquid that have enough energy can escape the liquid into the air
· Evaporation occurs for a range of temperatures; high temperatures increase evaporation, low temperatures decrease evaporation
· Evaporation only occurs from the surface of a liquid
· It is a slower process
· Because it removes the most energetic particles from a liquid the average energy of the remaining particles is decreased and the liquid cools down
· [cid:image007.png@01CC9575.884BC100]

See the full gallery on Posterous

Game

Click to play

Click to Run

5.7 and 5.8

· What are the 6 processes shown by the arrows?
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Solid --> Liquid: Melting
Liquid --> Gas: Boiling
Gas --> Liquid: Condensing
Liquid --> Solid: Freezing
Solid --> Gas: Desublimation/ Deposition
Gas --> Solid: Sublimation

5.7 and 5.8

· 5.7 understand that a substance can change state from solid to liquid by the process of melting
· 5.8 understand that a substance can change state from liquid to gas by the process of evaporation or boiling
· Questions from Collins p.112
· Answer in Bullet Points!

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· Use following pages from Collins as a resource to help you

Q1 a) -Particles in solids are stronger and fixed together
-Gases and liquids have a weaker bond between particles
b) -The particles in liquids and solids are closer together and more compact than the particles in a gas
-The particles in gases are weak so they can move around freely and spread out to fill their container

Q3)
Boiling=
-Done by humans and the liquid needs to be heated up to their boiling point
-Boiling happens quickly
-Boiling occurs throughout a liquid

Evaporation=
-Evaporation happens naturally when a liquid is left in the open air
-Only the particles on top evaporate because they have enough energy
-Evaporation doesnt need a fixed temperature (liquid doesnt need a boiling point)
-It is a slow process
-Because it removes the most energetic particles from a liquid the average energy of the remaining particles is decreased and the liquid cools down

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5.7 and 5.8 Experiment - Cooling Curve of Stearic Acid using datalogger

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states of matter drag and drop plenary.swf Download this file

Fill the trucks - Properties of s,l,g.swf Download this file

5.9 and 5.10 starter

· 5.9 recall that particles in a liquid have a random motion within a close-packed irregular structure
· 5.10 recall that particles in a solid vibrate about fixed positions within a close-packed regular structure
· Complete the missing words in the table below
· Cut and paste the particle images into the table

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State

Particle

Picture

Arrangement of Particles

Motion of Particles

Other Properties

Solid:
· closely packed
· regular pattern

· vibrate about a fixed position

· fixed shape
· not easily compressed since particles are closely packed
· Strong bonds

Liquid:
· closely packed
· no pattern

· free to flow over each other

· takes shape of its container
· can be poured
· not easily comressed since particles are closely packed
· Weak bonds

Gas:
· widely spaced
· no pattern

· very fast moving
· random directions

· fills its container
· can be poured
· easily compressed since its particles are far apart
· Very weak bonds

s,l,g animation.swf Download this file

See the full gallery on Posterous

5.6 Questions

Collins, p.107

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Note: ρfresh water = 1,000kg/m3; g = 10N/kg
Q5=
change in p = h x p x g
250000-100000= h x 1000 x 10
h = 150000 / (1000 x 10)
h=15m

Q6=
?

5.6 Demo - squirting water column

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· The bottom hole squirts water the furthest
· Because the water at the bottom has the greatest pressure
· Because in the formula ∆p = h × ρ × g, ρ is constant, g is constant and h is large
· So ∆p = large

5.6

· 5.6 recall and use the relationship for pressure difference:

pressure difference = height × density × g
∆p = h × ρ × g

∆p = pressure of the fluid (N/m2 or Pa)
h = height of the fluid (m)
ρ = density of the fluid (kg/m3)
g = gravitational field strength (N/kg)

5.5 Demo 2 - Collapsing Bottle

· Collapsing Bottle

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5.5 Demo 1 - Magdeburg Hemispheres

· Magdeburg Hemispheres

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· And here are the horses I was talking about! http://www.youtube.com/watch?v=7bJkaFByiA0&feature=related

5.5

5.5 understand that the pressure at a point in a gas or liquid which is at rest acts equally in all directions

5.4 Harder questions on Pressure

5.4 Harder questions on Pressure

07 October 2011

16:30

·         Collins, p.107, Q.4.

1^st person à p= Force/area = 400N/0.0025=160’000 Pa = 160kPa

Elephant à p = Force/area = 5000N/(piex10^2)

                                                       = 5000/0.0314=159’000 Pa = 159 kPa

2^nd Person à p= Force/area=400N/0.00005= 8’000’000 Pa =8000 kPa

5.4 Model answers to Written questions

<<Answers to written questions.ppt>>

See the full gallery on Posterous

Answers to written questions.ppt Download this file

5.4

·         5.4 recall and use the relationship between pressure, force and area:

        pressure = force / area

                  p = F / A

5.4 Starter

See the full gallery on Posterous

Starter.ppt Download this file

5.2 Harder Questions

5.2 Harder Questions

07 October 2011

07:46

·         Collins p.106 Q.1-3. (Table of densities below)

Q1) 1.depends 2. Float 3.Sink 4.float 5.sink 6.sink 8.float

Q3) mass = 1930g

         Density = 19.3

`

         P = m / V

         19.3 = 1930 / V

         V = 1930 / 19.3 = 100cm(cubed)

         800+100 = 900cm(cubed)

 

5.3 Plenary

Drag'n'Drop Density (in kg per m3).swf Download this file

Remember: 1g/cm³ = 1,000kg/m³

5.3 Plenary 2 Corrected!

·         How can you make a cannonball float?

Explanation below…

 

 

 

 

Density of Iron =  7.9g/cm³ or 7,900kg/m³

Density of Mercury =  13.6g/cm³ or 13,600kg/m³

Density of an irregular solid

1)Measure the volume of the rock using “displacement” in a “Eureka”

2)Measure the mass

3)calculate the density (p = m / V)

Volume = 2.5ml

Mass = 7.3g

Density = 7.3/2.5 = 2.9g/cm(cubed)

5.3 Plenary 2

5.3 Plenary 2

04 October 2011

14:06

·         How can you make a cannonball float?

Explanation below…

 

 

 

 

Density of Mercury =  7.9g/cm³ or 7,900kg/m³

Density of Iron =  13.6g/cm³ or 13,600kg/m³

Density of Water

How to measure a density of a liquid:

-Measure the mass (total mass – mass of the measuring cylinder)

-calculate the volume

-use the equation (p = m / V)

Mass(oil)=15.3g

Volume=18.0ml

Density = 15.3/18.0 = 0.85cm(cubed)

Keywords - Topic 5

unit 5 keywords.doc Download this file

p = m/v

V= volume (w x l x h)

M = mass grams

W = width

L = length

H = height

Mass = 575.2

W=5cm

L=5cm

H=2cm

V=50cm(cubed)

P=m/v

P=575.2/50 = 11.504g/cm(cubed)

5.2

Density formula.ppt Download this file

·         5.2 recall and use the relationship between density, mass and volume:

          density = mass / volume

                  ρ = m / V

Review of test

1)b Explain how a blanket on your bed reduces the heat transfer from your body

-insulation

-heat gets trapped in blanket

-convection

3)a the energy from wood and coal comes from the SUN (energy source)

c. disadvantage of burning wood – Land loss = Animal lose their habitat à need to migrate

d. non renewable sources:

-Nuclear

-Crude oil

-Natural gases

4)b. Linear kinetic energy is transferred to Electrical energy

6)c. TOTAL energy in = TOTAL energy out

7)d. Transferred to heat energy in her body

8)c. Shiny surfaces

9)a.iv GPE=KE

piha, mission bay, Auckland

Coe questions

PFY p.121

A)50x10=500N

b)GPE=mgh

=50x10x4 = 2000J

c)KE= 1/2m v^2

2000=25 x v^2

80J=v^2

Collins, p.91

Q3: a) GPE=mgh

=35 x 10 x 30

= 10500J

B) KE=1/2m v^2

10500=1.5 x v^2

600J=v^2

c) Because there is friction between the sledge and the ice (=heat energy)