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Idaho Public Television about Gravity(click on the picture):

 

 

Forces

Forces give an object the energy to move, stop or change its direction.

 

 

Types of forces:

1. Contact forces: There's a contact between two objects, two people or a person and an object.

• To push: to move an object forwards.

• To pull: to move an object backwards.

 

      2. Non-contact force: no contact takes place.

 

•  Gravity:  a force that attracts an object to another.

         It is the force that pulls everything towards the Earth's surface.

• Magnetism: It is the force the magnets produce.

             



Simple machines

Simple machines and complex machines.

Complex Machines.

 Complex machines are two or more simple machines working together.

e.g. A car is a complex machine; there are many simple and complex machines working together and at the same time.

 

 

Simple Machines

Simple Machines

A simple machine is a  device for altering a force.

Simple Machines: lever, bar, pulley, inclined plane, screw, wheel, axle and wedge.

1. Lever:: A lever moves on a fulcrum

  

      2.   Wheel:    A wheel spins around an axle.

 

 

      

3.   Pulley: A pulley is a wheel with a rope.

 

 

 

4. Inclined plane:

 

 

 

 

5. Wedge

 

 

6. Screw 

7. Axle