Acceleration due to gravity is
an acceleration which is produced by gravitational pull of earth in a free
falling body. Acceleration due to gravity is also known as Acceleration of
freely falling body . We have formula of acceleration due to gravity is; g=GMe/Re2.
Acceleration due to gravity just depends on M= mass of earth , Re= distance of object from
centre of earth. So it shows that acceleration due to gravity is independent of
mass, shape and size of object. It does not matter how heavy object is. All
objects falling freely will face same acceleration. But acceleration of an
object changes with height. At the surface of earth, the value of g is 9.8 m/s2
or 32 ft/sec. The value of acceleration due to gravity decreases due to
increase in altitude above the earth surface.
The new absolute determination of acceleration due to gravity has been
researched at the National Physical Laboratory. They used a new method as the
symmetrical free motion of body moving under the action of gravity. They moved
a glass ball and timed its passage across two horizontal planes by flashing of
light and it will produced when it will passed between two horizontal slits
which are served to define the each plane optically and the ball focusing light
from any of the slits, which was illuminated upon the other one and they placed
a photomultiplier behind it. They measured the separation of two planes
interferometrically. They directly referred the meter by international
wavelength definition and the time was measured in terms of atomic unit of time
scale. The value of gravity was reduced to
981 181.75 mgal , as 1 mgal=10^-5 m/s2. The systematic errors are
considered to be very small; generally this error is due to air resistance. The
main contribution of the observed results comes from microseismic disturbances.