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

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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