Acceleration due to Gravity Video Lecture - Class 9

acceleration due to gravity freefall
when an object falls towards the earth
due to the Earth's gravitational force
it is called as freefall earlier it was
thought that the lighter bodies fall
slowly while heavier bodies Falls
rapidly for example if a feather and a
metal coin are dropped simultaneously
from roof the metal coin would reach
first and the feather later but it was
Galileo who has proved from his
experiments conducted from the Leaning
Tower of Pisa that objects of different
masses and sizes when dropped
simultaneously from the same height
would reach the ground at the same time
that is when an object is dropped from
height it experiences uniform
acceleration by the gravitational pull
of the earth and this acceleration does
not depend on the mass of the body let
us define acceleration due to gravity
the acceleration due to gravity is a
uniform acceleration produced in freely
falling body due to the influence of the
gravitational pull of the earth the
acceleration due to gravity is denoted
by G this value varies from one
celestial body to another for example
the acceleration due to gravity would be
different on the moon as compared to the
earth similarly you could have different
values for Jupiter and Pluto the unit of
G is same as the unit of acceleration
m/s to the power of minus 2 value of G
from the second law of motion force is
the product of mass and acceleration F
is equal to n a for freefall forces the
product of mass and acceleration due to
gravity G F is equal to mg we know from
universal law of gravitation F is equal
to G into M into M by d square n G is
equal to
into M into M by D square J is equal to
G M by d square where m is the mass of
the earth and D is the distance between
the object and the earth for objects
near or on the surface of the earth D is
equal to the radius of the earth R M G
is equal to G M into M by R square or G
is equal to G M by r square to calculate
the value of g we should put the values
of G m and R in the equation G is equal
to G M by r square universal
gravitational constant G is equal to six
point six seven three into 10 to the
power of minus 11 n M square kg to the
power of minus 2 M is equal to 6 into 10
to the power of 24 kg r is equal to six
point four into 10 to the power of 6 M G
is equal to GM by R square G is equal to
six point six seven three into 10 to the
power of minus 11 n m square kg to the
power of minus 2 into 6 into 10 to the
power of 24 kg by six point four into 10
to the power of 6 M whole square the
value of G is 9.8 m/s to the power of
minus 2