MACHINES UNIT 3 MACHINES MOVE THE WORLD Marta Vidal Vidal L8 L9 L10 L11

IS A/AN ….. A MACHINE? CHEESE GRATER u AXE SEE-SAW/

Let’s bet! Is a/an………..a machine? Write questions for all the objects and bet (from 1 to 5). Question Yes, it is a machine. No, it isn’t a machine. BET LOSS GAIN 1. Is a TV a machine?   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: Is a drier a machine? Is a cheese grater a machine? Is a computer a machine? Is an apple a machine? Is a screw nut a machine? Is a tow truck a machine? Is a book a machine? Is a washing machine a machine? Is a telephone a machine? Is a corkscrew a machine? Is an axe a machine? Is a see-saw a machine? Is a well a machine? Is a slide a machine? Is a radio a machine? Is an artichoke a machine? Is a police car a machine? Is a dog a machine? Grand total=

IT CAN WORK WITH MECHANICAL ENERGY WHAT IS A MACHINE? It is a device designed to make work easier. IT CAN BE SIMPLE IT CAN WORK WITH WIND ENERGY IT CAN BE COMPLEX OR COMPOUND IT CAN WORK WITH ELECTRICITY IT CAN WORK WITH MECHANICAL ENERGY IT CAN WORK WITH SUN 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 PULL 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 LEVER CAN 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 rock Bob Long stick Small rock

LOAD A big rock LOAD Bob EFFORT Long stick LEVER Small rock FULCRUM 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 EFFORT LEVER FULCRUM

At an appropriate distance the big rock moves easily. LOAD EASY TO MOVE EFFORT LEVER At an appropriate distance the big rock moves easily. FULCRUM

At an inappropriate distance the big rock doesn’t move. LOAD DIFFICULT TO MOVE EFFORT LEVER FULCRUM At an inappropriate distance the big rock doesn’t move.

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? We need two rulers: one long and one short. What do we do with the rubber? We use the rubber as a fulcrum for doing a lever. What is the big book for? We use the big book as a load. Which ruler do we use first? Start with the short ruler and then do the same process with the long ruler. What are the small books for? We use the small books as an effort. What is the ruler for? We use the ruler as a lever.

HANDS ON! LEVER MATERIALS 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! LEVER STEPS 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)? Known as Position number 1

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 EFFORT SMALL BOOKS LOAD BIG BOOK FULCRUM RUBBER

“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 FIRST CLASS LEVER SECOND CLASS LEVER THIRD CLASS LEVER NUTCRAKER TWEEZERS PLIERS SEE-SAW WHEELBARROW SHEARING SCISSORS SCISSORS BOTTLE OPENER TONGS

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.  

PULLEY It 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.  

MACHINES SIMPLE MACHINES LEVER SCREW PULLEY WEDGE HOW IT HELPS US WORK? MACHINES SIMPLE MACHINES PLIERS SCISSORS TO LIFT OR TO MOVE LOADS LEVER THINGS MOVE UP OR DOWN IT INCLINED PLANE TO MOVE LOADS WHEEL AND AXLE TO HOLD THINGS TOGETHER OR TO LIFT SCREW TO MOVE THINGS UP, DOWN OR ACROSS PULLEY TO CUT OR SPREAD AN OBJECT APART WEDGE

They are any combination of simple machines. To know more about Simple machines Compound machines They are any combination of simple machines. Two levers Two wedges SCISSORS

LET’S FIND MACHINES IN OUR SCHOOL PUPIL ITS NAME WE CAN USE IT TO… WE CAN USE THE……. TO… NAME OF THE SIMPLE MACHINE  MARIA JOSEP 1 SCISSORS WE CAN USE THE SCISSORS TO CUT DIFFERENT THINGS LIKE PAPER.   2 LEVERS 2 WEDGES   2 3 4 5 6 7 8

A COMPOUND MACHINE

OUR SIMPLE LAWN-SPRINKLER A ROCKING CHAIR ( A ) SQUEEZES A BULB ( B ) SPRAYING A SHIRT ( C ) THIS CAUSES IT TO SHRINK AND PULL THE STRING( D ) TIPPING THE SHELF (E) THE HOMEMADE BISCUIT ( F ) FALLS HEAVILY INTO THE NET (G ) CAUSING THE ROD ( H ) TO RAISE A COVER ( I) EXPOSING A MOUSE ( J ) A CAT CHASES THE MOUSE ( K ) THEREBY REVOLVING THE PLATFORM (L) EACH TIME THE LAUGHING HYENA (M ) REVOLVES HE IS TICKED ON THE NOSE BY FEATHER BALL ( N ) 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 purpose To look at the materials To look at the idea Amazing !

Step-by-step process to build a compound machine Phase Step What do you do? Choose two partners 1 First Second Choose a theme for the machine Third Make a drawing/ sketch of a machine Fourth Write a list of materials and tools needed. 2 Fifth Make the machine. Sixth Make two lists one for the verbs and one for the nouns. Seventh Use verbs to describe the action of the parts of the machine. Order the different parts of the process. Eighth Write the steps of the movement of the different parts of the machine. Ninth 3 Explain the machine function to other groups. Tenth Finally Give your opinion as a group about the process of building the machine.