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## Level 1 Science As 90940 Aspects of Mechanics: Basic speed calculations

Here are the bullet points from the achievement standard that tell us what work we have to cover in distance and speed calculations.

Aspects of mechanics will be limited to a selection from the following:
Distance, speed, interpretation of distance and speed time graphs, average acceleration and deceleration in the context of everyday experiences such as journeys, sport, getting going. The relationships v = Δd/Δt. a=Δv/Δt.
• Mass, weight and the acceleration due to gravity, balanced and unbalanced forces, in the context of everyday experiences such as being stationary, moving at constant speed, accelerating. The relationship Fnet = ma.
• Force and pressure in the context of everyday experiences. The relationship P = F/A.
• Work and power, gravitational potential energy, kinetic energy, and the conservation of mechanical energy in free fall situations in the context of everyday experiences such as sports performance, dropping things, tossing balls. The relationships ΔEP = mgΔh EK = 1/2mv2 W = Fd P = W/t.

Homework.

Tackle the worksheet on basic speed calculations. You need to be confident of this before you go any further.

## Hot Air Balloon Flight.

The Balloon Expedition Company of New Zealand  take you on flights over Auckland’s north west. They pick you up at the Westgate Centre and transport you to the take off point. About half an hour is required to partially inflate the balloon with cold air then heat it up with three giant bunsen burners till the balloon has neutral buoyancy.  Its time to board the basket ready for lift off.

The air in the envelope is very hot, about 95 degrees celcius so the top of your head can get cooked if you are directly under the opening. An hour later after gently floating with the breeze (there is no wind, you move with the air), Darryl a very experienced pilot puts you down gently in a field somewhere out west. The destination is a pot luck affair and is determined by wind speed, wind direction and flight duration. Landing is a stressful time for Darryl as not all property owners appreciate a 5,000 cubic metre balloon dropping into the back field as they are having breakfast. The farm owners were friendly where we landed but apparently if we had flown over the fence into the next field we would have received a  frosty reception.

What the lovely people at the Balloon Expedition Company don’t tell you is that you have to pack the ballon back into its crate. Surprisingly it is no more difficult than rolling up a tent and putting it in its bag. The drive back to Westgate in the jeep is almost as exciting as the balloon flight and the champagne breakfast is first class.

Darryl’s offsider tried to tell us that champagne breakfasts were invented by early balloonists as a means of placating irate peasants when they landed in the middle of their crop fields…..hmm maybe.

Balloons are are designed so that they can reach a height of 100 meters in about a minute. Sixth form students should be able to answer questions about the rate of climb.

• what is the upwards acceleration?
• How fast is the balloon travelling after the first minute
• If you check out the combined weight of the balloon you should be able to calculate the size of the buoyant force

How big a balloon do you need to lift the combined masses of the envelope, basket, burners, gas cylinders and passengers? It turns out that the calculation is quite straightforward.

A combination of balloon volume and  temperature difference between the air inside the envelope and the air outside determines the lifting force and approximately 4.073 cubic meters of hot air are needed to lift each kilogramme of  mass.

This figure can be plucked quite literally out of the air using the ideal gas equation with a number of  assumptions about variables. Have a look at the science,  Archimedes had it all figured out 2022 years ago.

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Kavanagh of Australia manufactured the balloon used in the video clip. The balloon was an E Type-20 Gore model. The envelope volume was 180,000 cubic feet or 5,100 cubic meters.(1 cubic foot=0.02832 cubic meters),

A gore is a segment of a three dimesional object fabricated from 2 dimensional material.

## Bacterial Basics

Check out the following:

• Bacterial basics
• How bacteria live: Extra cellular digestion
• Watch a white blood cell chase a bacterium and absorb it…a horrible end
• Bacteria dividing

# NCEA Level 1 Geology: The Rock cycle and erosion and transport by glaciers

As the glacier rips rocks away from the sides of the valley it can leave a polished surface with gouge marks. 400 years in this grinding machine can turn rocks into flour.

Glaciers move slowly but relentlessly down valleys gouging out huge volumes of rock as they go. It takes about 400 years for snow collecting at the top of Fox glacier to reach the Fox river at the bottom.

As the glacier rips rocks away from the sides of the valley it can leave a polished surface with gouge marks. 400 years in this grinding machine can turn rocks into flour. Look at the colour of the water coming out the end of the glacier in the last video. Rocks carried by the glacier get dumped at the front and the sides when the ice melts.
Valleys formed by glacier erosion have a characteristic U shape.

## gaming:Nintendo Wii in the science classroom

Many games are driven by physics engines that mimic motion in the real world in a virtual counterpart. Phun discussed earlier is a simple 2D example. A number of classes had a brief look at the technology behind the Nintendo Wii and the physics concepts underpinning the games. The boxing game will have to be banned in future as students let loose in a virtual world were determined to punch each others’ lights out risking a virtual school suspension