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Natural sciences

Energy transfers and forces

Educator section

Memorandum

Observations:

(i) The smoke rises.

(ii) The smoke rises.

(iii) The smoke rises.

Conclusion:

Hot air rises.

During the day the land heats up more rapidly than the sea. The warm air above the land rises. Cooler air above the sea flows to the land to fill the place of the warm air. This is how sea winds originate.

At night the land cools down more rapidly than the sea. Therefore the air above the sea is warmer and rises. Cooler air from above the land flows to the sea to take the place of the warmer air. This is how a land-wind (offshore wind) originates.

Leaner section

Content

Ativity: to explain convection as a natural phenomenon [lo 1.2, lo 1.3]

(b) Convection

Convection is the main way in which heat moves through liquids. Water is a poor conductor of heat, but a kettle does manage to let water boil quickly. The reason is that liquids are able to move. Water rises when it becomes warm. The colder water then sinks down to take the place of the warmer liquid that is rising. The accompanying illustration shows how the circular movement, the convection current, distributes the warmth through the liquid until all the water is hot enough to come to a boil (100°C – boiling point for water at sea level).

Although air is a poor conductor of heat, it is possible to heat a room with the help of a heater. Take a burning candle. Note the direction of the smoke while you

(i) hold the candle in an upright position ___________________________________

(ii) hold the candle at an angle ___________________________________________

(iii) Hold the candle upside-down _________________________________________

Have you noted your observations? What do you deduce from this?

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As warm air rises, convection also occurs in nature. Have you ever thought about the origins of wind? Warm air rises and cold air moves to take its place.

Consider the principle of convection currents in air to help you distinguish between land and sea winds. You could make a sketch to help explain your observations.

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(c) Radiation

The transfer of heat by means of conduction or convection requires a solid substance, a liquid or a gas. There must be some substance to transfer heat energy. Such a transfer of energy through empty space is possible through radiation. Heat energy from the sun moves through space and the earth’s atmosphere and heats any object that it reaches.

If you drive along any road where you can see ahead into the distance on a hot day, it often seems as if there is water on the road. The hot tar of the road radiates heat. Using an electric heater to heat a room in winter is an example of the use of radiation in an everyday situation.

6. Conversion of energy

Which kind of energy is used when a boy hits a tennis ball?

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What kind of energy does the moving tennis ball have?

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This has probably made you suspect that energy can be changed. When there is a change in energy from one kind to another kind, we speak of the conversion of energy.

Assessment

Learning Outcome 1: The learner will be able to act confidently on curiosity about natural phenomena, and to investigate relationships and solve problems in scientific, technological and environmental contexts.

Assessment Standard 1.2: We know this when the learner conducts investigations and collects data: organises and uses apparatus/equipment or sources to gain and record information:

Assessment Standard 1.4: We know this when the learner evaluates data and communicates findings: generalises in terms of relevant aspects and describes how the data support the generalisation:

Questions & Answers

find the 15th term of the geometric sequince whose first is 18 and last term of 387
Jerwin Reply
I know this work
salma
The given of f(x=x-2. then what is the value of this f(3) 5f(x+1)
virgelyn Reply
hmm well what is the answer
Abhi
how do they get the third part x = (32)5/4
kinnecy Reply
can someone help me with some logarithmic and exponential equations.
Jeffrey Reply
sure. what is your question?
ninjadapaul
20/(×-6^2)
Salomon
okay, so you have 6 raised to the power of 2. what is that part of your answer
ninjadapaul
I don't understand what the A with approx sign and the boxed x mean
ninjadapaul
it think it's written 20/(X-6)^2 so it's 20 divided by X-6 squared
Salomon
I'm not sure why it wrote it the other way
Salomon
I got X =-6
Salomon
ok. so take the square root of both sides, now you have plus or minus the square root of 20= x-6
ninjadapaul
oops. ignore that.
ninjadapaul
so you not have an equal sign anywhere in the original equation?
ninjadapaul
hmm
Abhi
is it a question of log
Abhi
🤔.
Abhi
I rally confuse this number And equations too I need exactly help
salma
But this is not salma it's Faiza live in lousvile Ky I garbage this so I am going collage with JCTC that the of the collage thank you my friends
salma
Commplementary angles
Idrissa Reply
hello
Sherica
im all ears I need to learn
Sherica
right! what he said ⤴⤴⤴
Tamia
hii
Uday
hi
salma
what is a good calculator for all algebra; would a Casio fx 260 work with all algebra equations? please name the cheapest, thanks.
Kevin Reply
a perfect square v²+2v+_
Dearan Reply
kkk nice
Abdirahman Reply
algebra 2 Inequalities:If equation 2 = 0 it is an open set?
Kim Reply
or infinite solutions?
Kim
The answer is neither. The function, 2 = 0 cannot exist. Hence, the function is undefined.
Al
y=10×
Embra Reply
if |A| not equal to 0 and order of A is n prove that adj (adj A = |A|
Nancy Reply
rolling four fair dice and getting an even number an all four dice
ramon Reply
Kristine 2*2*2=8
Bridget Reply
Differences Between Laspeyres and Paasche Indices
Emedobi Reply
No. 7x -4y is simplified from 4x + (3y + 3x) -7y
Mary Reply
how do you translate this in Algebraic Expressions
linda Reply
Need to simplify the expresin. 3/7 (x+y)-1/7 (x-1)=
Crystal Reply
. After 3 months on a diet, Lisa had lost 12% of her original weight. She lost 21 pounds. What was Lisa's original weight?
Chris Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
China
Cied
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
I'm interested in nanotube
Uday
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
AMJAD
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
AMJAD
what is system testing
AMJAD
what is the application of nanotechnology?
Stotaw
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
Azam
anybody can imagine what will be happen after 100 years from now in nano tech world
Prasenjit
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
Azam
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
Prasenjit
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
Damian
silver nanoparticles could handle the job?
Damian
not now but maybe in future only AgNP maybe any other nanomaterials
Azam
Hello
Uday
I'm interested in Nanotube
Uday
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
Prasenjit
can nanotechnology change the direction of the face of the world
Prasenjit Reply
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
Ali Reply
the Beer law works very well for dilute solutions but fails for very high concentrations. why?
bamidele Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Natural sciences grade 7. OpenStax CNX. Sep 16, 2009 Download for free at http://cnx.org/content/col11077/1.1
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