Question

I want answer for this question for class 9th chapter gravitation

Answer 1

Think that an object of mass, m, is situated on the Earth s surface. Then the radius of the Earth=distance from the centre of the Earth to the object. Then,

From Newtons Law of Gravitation,

F=G.m.M/r^2   , where M: Mass of the Earth  ...(1)

Suppose the mass, m experiences g, accleration due to gravity. Then

Also from Newtons 2nd law,

F=m.g ....(2)

We can equate eq. (1) and (2),

m.g=G.m.M/r^2          

m on the both sides are cancelled, hence

g=G.M/r^2

Using the above eq:

g=6.7*10^-11*6*10^24/(6.4*10^6)^2

g=9.8m/sec

Answer 2

hope it may help you dear