# Gravitation

**Universal Law of Gravitation**

Gravitational Force is independent of the medium. The gravitational force inside a body is zero.

**Gravitational Constant **

**Acceleration due to Gravity **

**Variation with Height **

**Variation with Depth**

for every percentage decrease in radius, with mass constant; there is 2% increase in acceleration due to gravity.

**Variation with Latitude**

**Relation between Variation of height and depth **

If acceleration due to gravity is same at a certain height and depth;

then d = 2h

**Gravitational Field Intensity **

Gravitational field is the field of attraction around a mass. Gravitational Field Intensity is the amount of Force experienced by an object of unit mass in a gravitational Field.

**Gravitational Potential Energy **

Gravitational Potential Energy is the work done in bringing a charge of unit mass from infinity to a point against the gravitational field.

**Gravitational Potential **

Gravitational potential is the amount of work done per unit mass in a gravitational field.

Gravitational Potential is always directed opposite to Gravitational Field.

**Cases of Potential:**

**1.Due to point mass:**

The graph will be negative, curved and parallel to V and r axes.

**2.Inside a Solid Sphere:**

The graph is negative, parabolic.

**3.Outside a Solid Sphere:**

**4.Due to a Spherical Shell:**

**5.On the Axis of a Ring****:**

**Kepler's Laws**

Law of Orbits Kepler's Law of Orbits states that all planets revolve around the sun in elliptical orbits with sun as the focus.

**Law of Areas **

Kepler's Law of Areas states that a planet sweeps equal Areas in equal intervals of time around the sun.

**Law of Periods **

Kepler's Law of Periods states that the square of Time Period is directly proportional to the cube of Distance.

**Critical Velocity **

**Time Period **

**Binding Energy **

**Escape Velocity **

The escape velocity remains independent of angle of projection. Escape Velocity for an object on earth is 11.2 km/s.

**GRAVITATIONAL POTENTIAL & FIELD DUE TO VARIOUS OBJECTS**