MACHINES
MACHINES MOVE THE WORLD
UNIT 3
Marta Vidal VidalL8 L9 L10 L11
IS A/AN ….. A MACHINE?
• uCHEESE GRATER
SEE-SAW/AXE
QuestionYes, it is a machine.
No, it isn’t a machine.
BET LOSS GAIN
1. Is a TV a machine? 5 0 5
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20. Are scissors a machine?
TOTAL: Grand total=
Let’s bet! Is a/an………..a machine? Write questions for all the objects and bet (from 1 to 5).
Is a see-saw a machine?
Is a well a machine?
Is a slide a machine?
Is a radio a machine?
Is a dog a machine?
Is a screw nut a machine?
Is a tow truck a machine?
Is a book a machine?
Is an axe a machine?
Is an apple a machine?
Is a computer a machine?
Is a cheese grater a machine?
Is a drier a machine?
Is an artichoke a machine?
Is a police car a machine?
Is a washing machine a machine?
Is a telephone a machine?
Is a corkscrew a machine?
WHAT IS A MACHINE?It is a device designed to make work easier.
IT CAN WORK WITH MECHANICAL
ENERGY
IT CAN BE COMPLEX OR COMPOUNDIT CAN BE SIMPLE
IT CAN WORK WITH
ELECTRICITY IT CAN WORK WITH
SUN ENERGY
IT CAN WORK WITH WIND ENERGY
IT CAN WORK WITH CHEMICAL
ENERGY
WHAT IS WORK?WORK is done when a FORCE moves something.
If you use a PUSH or a PULL to move an object you are doing WORK.
PUSH PULLFORCE FORCE
OBJECT
When we do work we use energy.
Law of conservation of energy.
“Energy can neither be created (produced) nor destroyed by itself.
It can only be transformed.”
HANDS ON! EXERCISE 1 LEVERCAN WE LIFT THIS PENCIL?
CAN WE LIFT THIS CHAIR?
CAN WE LIFT A CAR?
CAN BOB LIFT THIS BIG ROCK?
Let’s see !!
Bob needs a little help
He needs a long stick
and
a small rock
Let’s see !A big rockBob
Small rock
Long stick
Yes, Bob can lift the rock with the help of the stick and the small rock.
A STICK + A SMALL ROCK= A SIMPLE MACHINE
IT IS CALLED A LEVER
A big rockBob
Small rock
Long stick
LOADEFFORT
LEVER
FULCRUM
LOAD
EFFORT
LEVER
FULCRUM
At an appropriate distance the big rock moves easily.
EASY TO MOVE
LOAD
EFFORT
LEVER
FULCRUM
At an inappropriate distance the big rock doesn’t move.
DIFFICULT TO MOVELOAD
EFFORT
LEVER
FULCRUM
HANDS ON! LEVER• Ask some questions about the experiment.
PROBLEM:
• Can we do the same work with less effort?
How many rulers do we need?
What do we do with the rubber?
What is the big book for?
Which ruler do we use first?
What is the ruler for?
What are the small books for?
We need two rulers: one long and one short.
We use the rubber as a fulcrum for doing a lever.
We use the big book as a load.
Start with the short ruler and then do the same process with the long ruler.
We use the ruler as a lever.
We use the small books as an effort.
HANDS ON! LEVERMATERIALS Write down the materials that you need to create the lever.
- Long ruler- Short ruler- A rubber- A big book- Small books- A pencil
HANDS ON! LEVERSTEPS
1. Predict: What is the best position of the rubber (as a fulcrum) to lift the big book with less effort (less small books)?
Predict: Which is the best ruler for lift the big book with less effort?
2. Prepare all the materials.
3. Start with the short ruler.
4. Try different positions for the rubber (fulcrum).
5. What is the best position of the rubber (as a fulcrum) to lift the big book with less effort (less small books)?
6. Change the short ruler for the long ruler and repeat the process.
7. What is the best ruler to lift the big book with less effort?
What is the best position of the rubber (as a fulcrum) to lift the big
book with less effort (less small books)?
Position number 1
Known as
What is the best ruler to lift the big book with less effort?
• It is the long ruler because it multiplies the effort applied.
LEVER
FULCRUMRUBBER
EFFORTSMALL BOOKS
LOAD BIG BOOK
“Give me a lever long enough; a fulcrum strong enough and I’ll move the world.”
Archimedes
LAW OF THE LEVER
“Magnitudes are in equilibrium at distances reciprocally proportional to their weights.”
Archimedes
Força, Equilibri, Valor i Seny!
Force, equilibrium, courage and wisdom!
LEVER
It’s a rigid object that is used with an appropriate fulcrum to multiply the effort applied on a load.
Fulcrum: a support on which a lever pivots.Load: resistance force (weight and gravity).Effort: force needed to move an object.
THERE ARE 3 KINDS OF LEVERS
Identify in the pictures:FULCRUM: green dot EFFORT: red arrow LOAD: blue arrow/dot
BOTTLE OPENER
Simple machine: LEVER
THIRD CLASS LEVERSECOND CLASS LEVERFIRST CLASS LEVER
PLIERS
SEE-SAW
SCISSORS BOTTLE OPENER TONGS
SHEARING SCISSORSWHEELBARROW
NUTCRAKER TWEEZERS
Other simple machines
INCLINED PLANE
It is an inclined surface used to raise an object. It decreases the effort.
WHEEL AND AXLE
It is a wheel with a rod, called and axle, through its centre: both parts move together.
SCREW
It is an inclined plane wrapped around a central shaft. The Rotational motion of the central shaft causes a linear upwards motion of the screw.
PULLEYIt is a wheel or set of wheels around which a single rope passes to move a load with a smaller effort.
WEDGE
Wedges are moving inclined planes which split or separate a load.
LEVER
INCLINED PLANE
WHEEL AND AXLE
SCREW
PULLEY
WEDGE
TO LIFT OR TO MOVE LOADS
THINGS MOVE UP OR DOWN
IT
TO MOVE LOADS
TO HOLD THINGS TOGETHER OR TO
LIFT
TO MOVE THINGS UP, DOWN OR
ACROSS
TO CUT OR SPREAD AN
OBJECT APART
PLIERS SCISSORS
HOW IT HELPS US WORK?SIMPLE MACHINES MACHINES
To know more about
Simple machines Compound machinesThey are any combination of
simple machines.
Two levers
Two wedges
SCISSORS
LET’S FIND MACHINES IN OUR SCHOOL
PUPIL ITS NAMEWE CAN USE IT TO…WE CAN USE THE……. TO…
NAME OF THE SIMPLE MACHINE
MARIAJOSEP
1 SCISSORSWE CAN USE THE SCISSORS TO CUT DIFFERENT THINGS LIKE PAPER.
2 LEVERS2 WEDGES
2
3
4
5
6
7
8
A COMPOUND MACHINE
OUR SIMPLE LAWN-SPRINKLERA ROCKING CHAIR ( A ) SQUEEZES A BULB ( B )
A CAT CHASES THE MOUSE ( K )
TO RAISE A COVER ( I)
EXPOSING A MOUSE ( J )
CAUSING THE ROD ( H )
FALLS HEAVILY INTO THE NET (G )
THIS CAUSES IT TO SHRINK AND PULL THE STRING( D )
THE HOMEMADE BISCUIT ( F )
TIPPING THE SHELF (E)
SPRAYING A SHIRT ( C )
THEREBY REVOLVING THE PLATFORM (L)
REVOLVES HE IS TICKED ON THE NOSE BY FEATHER BALL ( N )
EACH TIME THE LAUGHING HYENA (M )
CAUSING HIM TO LAUGH SO HARD HE CRIES – THE SPEED OF THE REVOLUTIONS SCATTERS TEARS OVER LAWN
CAUSING THE GRASS TO GROW.
Some examples of compound machines
• Some school projects• Different materials• Pythagoras switch• Advertisements
To look at the purposeTo look at the materialsTo look at the ideaAmazing !
Step-by-step process to build a compound machine
What do you do?Step
Choose two partners
Choose a theme for the machine
Make a drawing/ sketch of a machine
Write a list of materials and tools needed.
Give your opinion as a group about the process of building the machine.
Write the steps of the movement of the different parts of the machine.
Make two lists one for the verbs and one for the nouns.
Order the different parts of the process.
Make the machine.
Explain the machine function to other groups.
Second
Third
Fourth
Fifth
Sixth Seventh
Eighth
Ninth
Finally
First
Use verbs to describe the action of the parts of the machine.
Tenth
1
2
3
Phase