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Grade 7

Working with wind and water

Module 7



The WATER-WHEEL was one of the first examples of a motor or a machine that could be operated by making use of running water. A water-wheel is made of a large wooden wheel with blades or paddles that turn on an axle. It utilises the force of running or falling water to make a machine work. The axle of the wheel is connected to the machine, and the power that is generated by the wheel is conveyed to the machine. A water-wheel is therefore an example of a wheel and an axle, because the force of the water on the blades causes a powerful propelling or driving force on the central axle.

The first kind of water-wheel was built in Greece in 200 BC. However, it was not satisfactory, because it turned on a vertical axle and needed fast-flowing water. Because it was small, the wheel generated only enough power for one family to grind their wheat for flour. Marcus Vitruvius Pollio designed a better water wheel in 35 BC.

There were mainly three types of water wheels with axles that turned horizontally. They were larger and could generate more power. One type, the undershot wheel , was built over running water. It had flat blades and the water ran along the LOWER PART or BASE of the wheel, retaining the same level all the time. The flow of the water against the flat blades at the base of the wheel made the wheel turn.

Undershot wheel

Another kind of wheel, the overshot water-wheel, had blades that were shaped like little bowls. These “bowls” could catch up the water that was fed to the wheel through a channel or trough. Thus the water cascaded over the blades from a trough ABOVE the wheel. The weight of the water in the bowls caused the wheel to turn faster than the undershot wheel that was powered by the weight of flowing water. Therefore, in the case of the overshot water-wheel the water fell on the wheel from above and flowed away on ground level.

Overshot water-wheel

In a centreshot water-wheel the water struck the blades in the CENTRE of the wheel.

Centreshot water wheel

In a hydroelectric power station the water cascades through a pipe into a dam, and the blades of the turbines are made to rotate. The pressure caused by the cascading water rotates the wheel so that it rotates in the same way as the water wheel. The turbine supplies

the power for a generator that generates electricity.

Questions & Answers

How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
How can I make nanorobot?
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
how can I make nanorobot?
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
While the American heart association suggests that meditation might be used in conjunction with more traditional treatments as a way to manage hypertension
Beverly Reply
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Source:  OpenStax, Technology grade 7. OpenStax CNX. Sep 10, 2009 Download for free at http://cnx.org/content/col11032/1.1
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