CBSE Class 11 Physics Gravitation Exam Notes

NEWTON’S LAW OF GRAVITATION

It sates that the gravitational force of attraction F betwen two point masses m1 and m2 is directly proportional to the product of their masses and is inversely proportional to the square of the distance r between the point masses.

where G is a constant and is called as Universal Gravitational Constant. G = 6.67 × 10^—11 Nm²/kg² It is a central force, which is always acting towards the line joing the masses

GRAVITATIONAL INTENSITY
Gravitational field Intensity: I, is defined as the force experienced by a unit mass placed at a distance r when placed in a gravitational field produced due to mass M.
I = GM/r ²

Gravitational field intensity due to spherical shell

Case-I : Inside the shell i.e. (r < R) There is a point P, which in at a distance r form in centre.E = 0
Case-II: At a point on the outer surface of the shell E = − GM/R² r where r is unit vector along radius away from centre

Case-III: At a point outside the shell E =-GMr/r²

Gravitational field due to solid sphere

Case-I: At a point P inside the solid sphere E = − G m/ R³ rr

Case-II: At a point on the surface of the solid sphere E = − Gm/ R² r
Case-III: At a point outside the solid sphere E = -GM/ r²r

Graphically it can be represented as,

GRAVITATIONAL POTENTIAL
V, at a point at a distance r in the gravitational field due to mass M is the work done in taking a unit mass from this point to infinity against force of attraction.
V = −GM/r

GRAVITATING POTENTIAL DUE TO A SPHERICAL SHELL

Case-I: At a point inside the shell
V = − GM/R

Case-II: At a point on the surface
V = − GM/R

Case-III: At a point outside the surface
V = − GM/r

Graphically, it can be represented as