Year 7 Discussion Board
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missviney
May 5, 2011 at 1:28 am
What is Density?
Density is a measure of mass per unit of volume.
The higher an objects density, the higher its mass per volume.
The higher an objects density the smaller the gaps between the particles.
Water has a higher density then oil.
We know this because oil floats on top of water.
Salt water has a higher density then an egg.
We know this because the egg floats on top of the salt water.
When two or more substances are added together:
The substance with the highest density will ‘sink’ as it has a higher mass to volume ratio or smaller gaps between particles.
The substance with the lowest density will ‘float’ as it has the smallest mass to volume ratio or larger gaps between particles.
You can calculate an object/substance’s density by dividing its total mass by its total volume.
There are also a heap of experiments that you can do at home
missviney
May 24, 2011 at 6:17 am
Year 7 Prac due date THIS FRIDAY 27th Changing State
missviney
June 22, 2011 at 7:02 am
Year 7J Class notes from Excursion
Page 84
1. Pumping
They run on bio-gas
Sewage is pumped in to plant
Methane: power
Generator (7): electricity
Sewage 99% liquid and 1% solid
Waste: poo, fertiliser, rubbish, rags, fish, lollipop sticks, cotton buds, toilet paper, cornflakes, urine, brush teeth, shower, bath, dishes, water etc.
6-8 hours for the sewage to arrive at the plant, morning 6-8 am
2. Screening
Solids and liquids, takes out all the solids,
Bar with teeth and sieving (different sizes)
3. Primary sedimentation Tanks
Sediment sinks to the bottom, heavier, molecules are bigger
Decanting
4-5 meters deep
(Cotton buds)
4. Aeration
Snake like
Bubbles (air) and no bubbles (no air)
Bacteria: Nitrogen
Encourages the growth of Sea weed: less sun light
Takes oxygen
Poo divers:
- to fix and maintain the tank
- Special suits
- Trained engineers
- Rope around them to be pulled back up, couldn’t see
2 m deep
Foam at the top: dead bacteria
5. Secondary Sedimentation Tanks
Circle shape
Filter, solids were left
6. Digester
Bacteria from our body
37 degrees
Sludge
Dark inside
Moist
Methane: electricity : 70% used to run the plant
7. Sterilisation and Discharge
Add chloride
Add fluoride
2 years: storage
DVD
4 year: raindrop
PICTURES
N drive…pictures available in a folder called year 7 excursion….along with websites on assignment sheet.