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Natural sciences

Grade 9

Energy, forces and machines

Module 24

Levers

Activity:

Identifying levers as mechanisms to identify energy transfer

[lo 2.2; lo 2.3; lo 2.4]

The operation of the simple appliances given above depends on the principle of the lever.

  • All levers have a PIVOTAL POINT or FULCRUM , a point where effort or power is applied (or the POWER POINT) , and an AREA OF LOAD called LOAD (L) .
  • The relevant symbols are:
  • P = point/fulcrum
  • E = effort/power
  • L = load
  • Levers are classified according to the position of the fulcrum.
  • There are three classes of levers.
  • Class 1 lever
  • Class 2 lever
  • Class 3 lever

CLASS 1: Fulcrum in the middle

e.g. a see-saw

CLASS 2 : Load in the middle

e.g. a wheelbarrow being pushed

CLASS 3: Effort/Power in the middle

e.g. a golf club or broom held for use

Identify the class of lever in each of the following examples:

a) You pick up a can of cold drink and raise it to your mouth.

b) You stand on the tips of your toes.

c) You hold a fishing rod, having hooked a large fish.

d) You row a boat using an oar.

Assessment of classification of LEVERS

Were you able to place the examples in categories?

[LO 2.2; LO 2.3]

Activity:

Calculating mechanical advantage

[lo 2.4]

Force × distance = load × distance

  • It is possible to calculate the mechanical advantage of a lever: the ratio of load to force provides this index.
  • We refer to this as mechanical advantage.

1. How would one be able to enhance the mechanical advantage of a class 1 lever?

  1. You have a nutcracker with the following dimensions:
  • You require 150 N to crack the nut.

a) Which FORCE is needed?

b) What is the mechanical advantage of the nutcracker?

[LO 2.4]

The Wheel

Activity:

Researching the invention of the wheel and evaluating as an example of human endeavour

[lo 1.1; lo 1.2; lo 2.1]

The invention of the wheel more than five thousand years ago resulted in a remarkable change in human performance of work.

The wheel is like a lever, except that the movement comprises rotation around an axle and not an up and down movement around a fulcrum.

Project dealing with the WHEEL

Work as a group and create a poster to represent the development of the wheel and to illustrate different ways of using wheels.

  • Did the Egyptians have wheels to assist them when they were building the pyramids?
  • How did they manage to perform all these tasks?

Assessment of RESEARCH on the WHEEL

Were you able to plan and execute the investigation and to evaluate it?Were you able to gain INSIGHT into the VALUE of human scientific endeavour?

[LO 1.1; LO 1.3; LO 3.1]

Assessment

LO 1: Scientific investigations:

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.

This is evident when the learner:

  • plans investigations;
  • conducts investigations and collects data;
  • evaluates data and communicates findings.

LO 2: Constructing Science Knowledge:

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

This is evident when the learner:

  • recalls meaningful information;
  • categorises information;
  • interprets information;

2.4 applies knowledge.

LO 3: Science, Society and the Environment

The learner will be able to demonstrate an understanding of the interrelationships between science and technology, society and the environment.

This is evident when the learner:

3.1 is able to show an appreciation of science as a human endeavour.

Memorandum

Activity

a) Class 3

b) Class 2

c) Class 3

d) Class 1

Activity

L.W. A study of levers is no longer required as part of the syllabus, but levers are referred to in this module to illustrate the transfer of energy from one body to another.

1. Reduce the force distance

2. a)

b)

Activity

Assess according to the learning outcomes and assessment standards indicated in the module.

Questions & Answers

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
Do somebody tell me a best nano engineering book for beginners?
s. Reply
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
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
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
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 9. OpenStax CNX. Sep 15, 2009 Download for free at http://cnx.org/content/col11069/1.1
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