Question

write expression for the gravitational force exerted on a point mass m located above, below the surface of the earth. hence deduce an expression for g on earth's surface. ​

Answer 1

Answer:

g=G X m/R^2.............0..

Answer 2

it is the acceleration produced in an object, when it is falling towards the centre of the earth, only under the influence of gravity.

consider an object of mass 'm 'lying at the surface of the earth.

from universal law of gravitation;

F = GMm/r^2 ----e1 (as the object is on the surface of the earth, 'd' becomes 'r'.)

from newtons second law of motion;

F = mg ------e2

from e1 and e2;

mg = GMm/r^2

(we remove ''m' from both sides.)

therefore, g = Gm/r^2

value of 'g' on the surface of the earth = 9.8 m/s^2