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Natural sciences

Energy transfers and forces

Educator section

Memorandum

a)

  • Iron
  • Copper
  • Aluminium
  • Lead

All four are good conductors, but copper, for example, is a better conductor than iron. Determine positions by doing an experiment. Try to use laboratory rods that are of the same size.

(b) An eiderdown (or down duvet) keeps one warm because body heat is poorly conducted by it. The air between the down is also a poor heat conductor. Bricks also have tiny holes that are filled with air. That makes a brick a poorer conductor of heat than for example copper, which is more solid/compact.

(c)

(i) Clay.

(ii) It conducts heat poorly from outside; therefore it will remain cooler inside than outside.

(iii) Wool is a poor conductor and therefore it keeps the body heat inside.

(iv) The learner should choose a good conductor for the bottom of the pot especially, in order to get the heat to the contents of the pot rapidly to speed up the preparation time of the contents. He/she should choose a poor conductor for the handles of the pot, so that one can handle the pot without having to use potholders or a cloth.

(v) Water is a poor conductor.

(vi) Tins are made of aluminium, which is a better conductor than glass.

Leaner section

Content

Activity 6: to compare the conductivity of various substances [lo 2.2]

(a) Test the following metals by warming them in a flame or in boiling water. Let each member of the group hold a different metal rod. Report it as soon as the heat reaches your hand. Arrange the metals in such a manner that the metal that is the fastest conductor – the one that gets hot first – is placed in the first position.

Metal Position
Iron _______________________
Copper _______________________
Aluminium _______________________
Lead _______________________

(b) Why is it that some substances are better conductors than other substances?

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(c) Use your knowledge of conduction to answer the following questions.

(i) Which metal would you use to build a hut that needs to be cool in summer – clay or corrugated iron?

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(ii) Why have you chosen this as the building material?

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(iii) Have you ever thought about the reason for wearing woollen clothing in winter? Try to explain why winter garments contain wool.

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(iv)You have an opportunity to design a pot for cooking food. Which materials would you use, and why? (Remember that a pot also needs handles!)

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(v) Why do we put a bottle of cool drink in cold water when we want to keep it cool?

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(vi) Try to explain why cool drink in a bottle would remain cold longer than cool drink in a tin.

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Assessment

Learning Outcome 2: The learner will know and be able to interpret and apply scientific, technological and environmental knowledge.

Assessment Standard 2.2: We know this when the learner categorises information: compares features of different categories of objects, organisms and events.

Questions & Answers

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
Commplementary angles
Idrissa Reply
hello
Sherica
im all ears I need to learn
Sherica
right! what he said ⤴⤴⤴
Tamia
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
is it 3×y ?
Joan Reply
J, combine like terms 7x-4y
Bridget Reply
im not good at math so would this help me
Rachael Reply
yes
Asali
I'm not good at math so would you help me
Samantha
what is the problem that i will help you to self with?
Asali
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
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
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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