viernes, 29 de abril de 2022

NS4: UNIT 6: FORCES AND MACHINES

 

UNIT 6: Machines and forces

6.1.- Forces and their effects

A force is a push or pull.

Ø  Non-contact forces

Non contact forces act from distance. They do not touch the object. The main examples are gravity and magnetism.

v Gravity.- It attracts all objects to the center of the Earth. Isaac Newton had his theory of gravity which changed the world.

v Magnetics.- It exists between magnetic minerals and metals. All magnets have a north pole and a south pole.

Ø  Contact forces

Two objects are in direct contact.

v Friction.- It is a forcé that makes objects slow down and stop. Example: ski.

v Buoyancy.- It is a force inside a liquid. Example: scuba diving.

            Forces can make objects change shape (plasticine) and change position (kick a ball).

6.2.-Simple machines

-A simple machine has a few o no moving parts.

- The load is the object you want to move.

- The effort is the forcé you apply.

- There are six types.

 An inclined plane.-When you move objects from one level to another.

Ø  A wedge.-It is made up of two inclined planes put together.

Ø  A pulley.-It is made up of a rope and one or more wheels.

Ø  A screw.-It consists of an inclined plane that goes around a cylinder.

Ø  A Wheel and axle.-An axel is in the center of a Wheel.

Ø  A lever.-It is a bar that moves on a fixed point called a fulcrum.

6. 3.-Complex machines

- Complex machines are made up of two or more simple machines. Example: a bicycle.

- A bicycle is made up of a frame, handlebar, brakes, gears, pedals, and wheels.

- People use all types of machines every day.

- Machines have the following functions:

·       Mechanical.-For moving an object.

·       Thermal.-For heating.

·       Information processsing.-For processing and transforming information.

-Machines need the energy to work such as water, The Sun, gas, and oil.

6.4.-Inventions and discoveries

There are inventions and discoveries from the past.

-        They improve medicine, entertainment, information, and better communication.

-        Examples are penicillin, the Wheel, TV, and  X-ray.

-        Technology improves everything but technological devices can cause problems.

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