Acceleration due to Free Fall
When a feather and a coin are dropped from the same height simultaneously, both objects fall because of the pull of gravity. However, the feather will fall much more slowly when compared to the coin. This is because of the air resistance acting on the feather.
Pause & think
What if both objects are to be released in a Place where there is no air resistance?
In 1971, an astronaut David Scott, Commander for Apollo 15 performed a simple experiment on the moon. He released a hammer and a falcon feather While on the moon , which has no atmosphere. He managed to show the world that both objects fell with the same acceleration in the absence of air. Both objects landed on the moon's surface at the same time.
IT, Visit this website below to witness Commander David Scott dropping hammer and a falcon feather on the surface of the moon http://www.hq.nasa.gov/alsj/a15/a15v_1672206.mpg
Pause & think
OK, if an object is free falling, it means:
(a) the effect of air resistance is negligible
(b) it experiences only pull of gravity
(c) its acceleration is approximately 10 m/s2
(d) every one second later, it will be faster than before by approximately 10 m/s.
The feather and coin experiment
Similar effects can be demonstrated on the earth when the objects are released in a glass tube where air can be removed.
When all the air has been removed from the glass tube, the feather and the coin which are released, will reach the bottom of the tube at the same time. This shows that without air resistance, objects of different weights fall with the same acceleration.
As the acceleration of the falling object in the absence of air is due to entirely to the effect of gravity, We call this acceleration due to gravity, or acceleration due to free fall, and is denoted by the symbol g.
A compact object with small surface area, which is dropped near to the surface of the earth, has an acceleration g of approximately 10 m/s2.
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