<< Chapter < Page Chapter >> Page >

Natural sciences

Planet earth and the universe

The earth

Educator section

Memorandum

Assignment 1:

  • Assess using the assessment matrix.

Assignment 2:

Main Ideas

  • Earthquake: evening of 29 September 1969.
  • Registers 6.5 on the Richter Scale.
  • Chaos in most places.
  • Rumbling grew louder and louder and was followed by tremendous quake.
  • The whole earth shuddered and people ran about panic stricken.
  • Rescuers used the Post Office as a base because it was the only place which had electricity.
  • Homes were badly damaged and people were badly injured.
  • Emergency aid streamed to the disaster towns and the police and army co-operated.
  • People were housed in tents and field hospitals were erected.
  • The water shortage was alleviated and food was supplied.
  • R13 million donated by the Disaster Committee

Assignment 3:

  • (sketch)

Assignment 4:

1. The Richter Scale is the instrument (scale) which seismologists use to measure the strength of an earthquake.

2. Seismologists are scientists who study earthquakes.

3. The place at which the shock waves first reach the surface of the earth is known as the epicentre.

4. If the pressure in the mantel under the crust builds up then magma is forced through weak places and cracks. These weak places then form volcanic pipes.

5. Active volcanoes are volcanoes which erupt from time to time.

Leaner section

Content

Activity: to analyse the structure of the earth and to measure movements in it (natural disasters) [lo 2.1, lo 2.3]

STRUCTURE OF THE EARTH

  • Scientists believe that Earth came into existence about 4 600 million years ago as a large cloud of gas and dust swirling around in space. While it was rotating it shrank to an extremely hot, liquid ball. The surface gradually cooled and a crust of solid rock formed which weathered to the mountains, soil and sand on which we live today.
  • Earth is continually changing. The land masses (continents) are not only moving, but new crust is forming all the time. The movement of the crust is called continental drift and it is still occurring. America, for example, is moving gradually away from Europe. This movement has already led to telephone cables under the Atlantic breaking.

FOUR LAYERS OF THE EARTH

  • The Crust

The crust is the outermost layer and has a thickness of from 5 km to 70 km. Under the oceans the crust can be as thin as 5 km and where there are mountains the crust can be as thick as 70 km. Beneath the crust there are three other layers. They are:

  • The Mantle

The mantle is 2 900 km thick. It is solid but contains slowly flowing currents of semi-melted metals.

  • The outer Core

The outer core consists of liquid metal and is responsible for the earth’s magnetic field. It is 2 240 km thick.

  • The inner Core

The inner core in the middle of the earth is probably solid and consists mainly of metals. The temperature is 3 700 degrees Celsius. Water boils at 100 degrees Celsius. The inner core has a diameter of 2 240 km.

The lava that flows from volcanoes comes from the mantle.

TASK 1: GROUP WORK

Use playing dough (four different colours) to make a model of Earth’s structure. The thickness of each layer should be more or less proportional to the actual thickness of the earth’s layer.

Questions & Answers

Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
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
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
research.net
kanaga
sciencedirect big data base
Ernesto
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.
Bharti
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
Daniel
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
Maciej
characteristics of micro business
Abigail
for teaching engĺish at school how nano technology help us
Anassong
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
NANO
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
s.
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.
Tarell
what is the actual application of fullerenes nowadays?
Damian
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.
Tarell
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.
Virgil
is Bucky paper clear?
CYNTHIA
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
NANO
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
SUYASH Reply
for screen printed electrodes ?
SUYASH
What is lattice structure?
s. Reply
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
Sanket Reply
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply

Get the best Algebra and trigonometry course in your pocket!





Source:  OpenStax, Natural sciences grade 7. OpenStax CNX. Sep 16, 2009 Download for free at http://cnx.org/content/col11077/1.1
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Natural sciences grade 7' conversation and receive update notifications?

Ask