SOLUCIONES DE ACTIVIDADES. NATURAL SCIENCE. UNIT 6: "MACHINES AND INVENTIONS".

GOOD MORNING!!!

1. A machine is something you use to make work easier.
   
    A simple machine has few or no moving parts.

    A complex machine is made up of simple machines.


2. Inclined plane.  Wheel and axle.     Lever.

    Wedge.              Pulley.              Screw.


3. Wheel and axle.   Screw, wedge.    Pulley.

    Lever, screw.   Inclined plane.    Screw, lever.


4. a) Wheel and axle.  b) Inclined plane.

    c) Wedge.                d) Pulley.

   e) Screw.                  f) Lever. 

5. People.          Electricity.            Fuel.

    Electricity.       Fuel.                 People.


6. Compass.         Telephone.        Wheel.

    Lightabulb.      Internet.


7. Compass: Navigation.

    Ligthbulb: Artificial light.

    Telephone: Speaking to people in different places.

    Wheel: Land transportation.

    Internet: World wide network of computers.


8. a) Communication revolution. b) Aeroplane.

    c) Steam engine.           d) Car.

    e) Smarphone.               f) Telegraph.

    g) Modern trains.           h) Morse code.


9. 2. This is a fridge. It is used for keeping food cold.

    3. This is a microwave. It is used for heating food.

    4. This is a washing machine. It is used for washing / cleaning clothes.

    5. This is a hoover / vacuum cleaner. It is used for cleaning the floor.