lee's classroom

(another MPPS global2.vic.edu.au weblog)

Forces: Friction

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Friction is a force between two surfaces when they are moving or sliding across each other. For example, when you try to push your hand across a table. Friction will make this difficult.

Friction works in the opposite direction to which the object is moving. Friction always slows a moving object down, and may even stop an object from moving.

The amount of friction depends the two surfaces.. The rougher the surface, the more friction, the smoother the surface, less friction.

Friction also produces heat. If you rub your hands together quickly, can you feel them get warmer?

The ways friction can help include:

  • preventing our shoes from slipping on the footpath when we walk
  • stopping car tyres from skidding on the road
  • allowing bicycle brakes to grip and slow or stop a turning wheel

Sometimes we want to reduce friction. For example, we use oil to reduce the friction between the moving parts inside a car engine. The oil holds the surfaces apart and can flow between them. The reduced friction means there is less wear on the car’s moving parts and less heat produced.

Ice causes very little friction, which is why it is easy to slip over on an icy day.

However, this is a good thing for ice skating and sledging.

 

 

 

Below are the videos we looked at in class:

Friction is a Force

https://www.youtube.com/watch?v=n2gQs1mcZHA

https://www.youtube.com/watch?v=ybpFEB6Mt88

Floating Rice Bottle — How to Float Rice in a Bottle Science Experiment !!

 

Another resource is:

http://www.bbc.co.uk/bitesize/ks2/science/physical_processes/friction/read/1/

 

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