Friday, June 10, 2011

Free fall


Objects fall because they are pulled towards the Earth by the force of gravity.

This force is known as the pull of gravity or the earth’s gravitational force.

The earth’s gravitational force tends to pull everything towards its centre.

Free fall 
An object is falling freely when it is falling under the  force of gravity  only. 
Objects and people will experience weightlessness during free fall.

Examples of objects not in free fall:

  1. A piece of paper does not fall freely because its fall is affected by air resistance.
  2. Flying birds because there is also an additional force of lift.
Examples of objects in free  fall:

  1. An object falls freely only in vacuum. The absence of air means there is no air resistance to oppose the motion of the object. In vacuum, both light and heavy objects fall freely. They fall with the same acceleration ie. The acceleration due to gravity, g.
  2. In a falling elevator. 
(gravitational acceleration,g  =  9.8 ms-2, in SPM often approximated g as 10 ms-2)


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