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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

what is math number
Tric Reply
x-2y+3z=-3 2x-y+z=7 -x+3y-z=6
Sidiki Reply
Need help solving this problem (2/7)^-2
Simone Reply
x+2y-z=7
Sidiki
what is the coefficient of -4×
Mehri Reply
-1
Shedrak
the operation * is x * y =x + y/ 1+(x × y) show if the operation is commutative if x × y is not equal to -1
Alfred Reply
An investment account was opened with an initial deposit of $9,600 and earns 7.4% interest, compounded continuously. How much will the account be worth after 15 years?
Kala Reply
lim x to infinity e^1-e^-1/log(1+x)
given eccentricity and a point find the equiation
Moses Reply
12, 17, 22.... 25th term
Alexandra Reply
12, 17, 22.... 25th term
Akash
College algebra is really hard?
Shirleen Reply
Absolutely, for me. My problems with math started in First grade...involving a nun Sister Anastasia, bad vision, talking & getting expelled from Catholic school. When it comes to math I just can't focus and all I can hear is our family silverware banging and clanging on the pink Formica table.
Carole
I'm 13 and I understand it great
AJ
I am 1 year old but I can do it! 1+1=2 proof very hard for me though.
Atone
hi
Adu
Not really they are just easy concepts which can be understood if you have great basics. I am 14 I understood them easily.
Vedant
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
If f(x) = x-2 then, f(3) when 5f(x+1) 5((3-2)+1) 5(1+1) 5(2) 10
Augustine
how do they get the third part x = (32)5/4
kinnecy Reply
make 5/4 into a mixed number, make that a decimal, and then multiply 32 by the decimal 5/4 turns out to be
AJ
how
Sheref
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
hi
Ayuba
Hello
opoku
hi
Ali
greetings from Iran
Ali
salut. from Algeria
Bach
hi
Nharnhar
A soccer field is a rectangle 130 meters wide and 110 meters long. The coach asks players to run from one corner to the other corner diagonally across. What is that distance, to the nearest tenths place.
Kimberly Reply
Jeannette has $5 and $10 bills in her wallet. The number of fives is three more than six times the number of tens. Let t represent the number of tens. Write an expression for the number of fives.
August Reply
What is the expressiin for seven less than four times the number of nickels
Leonardo Reply
How do i figure this problem out.
how do you translate this in Algebraic Expressions
linda Reply
why surface tension is zero at critical temperature
Shanjida
I think if critical temperature denote high temperature then a liquid stats boils that time the water stats to evaporate so some moles of h2o to up and due to high temp the bonding break they have low density so it can be a reason
s.
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
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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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