# Physics Assignment Help With Gravity

## 6.4 Gravity

**Variation in the values of ‘g’ on the surface of earth** is due to the following reasons

(a) **Due to shape of earth**: An structure of earth the gravity is given by . The earth is elliptical in shape. It is flatter at the poles and bulged out at the equator. Now, as , therefore the value of g at the equator is minimum and the value of g at the poles is maximum ( Radius at poles is < Radius at equator).

(b) **Due to rotation of earth** : Earth rotates about its axis therefore every object placed on the surface of earth also rotates about the same axis. If the observed value of g at the latitude l is represented by gl, then

where w is the angular velocity of rotation of the earth.

At equator l = 0º and hence cos l = 1 (minimum value of gravity)

At poles (maximum values gravity)

**Variation of ‘g’ above the surface of earth**: As we go above the surface of the earth, the value of ‘g’ decreases

(i) Consider a body of mass m at a height ‘h’ above the surface of earth. (Let Re is the radius of earth and Me is the mass of earth) if h << Re, then expanding binomially and neglecting higher power of h/Re, we get

or gn = (where )

### So near the surface of earth gravity varies linearly with height

**Variation of ‘g’ below the surface of earth**: The value of ‘g’ decreases as we go below the surface of earth because the effective mass of earth attracting the body decreases.

The value of ‘g’ at a depth x from the surface of earth is = g - Dg = g - gx/R

At the centre of earth x = R hence g = 0

The decrease in the value of ‘g’ at a depth ‘x’ below the surface of earth is Dg = (gx/R)

### Email Based Assignment Help in Gravity

We are the leading online Assignment Help provider. Find answers to all of your doubts regarding the Gravity. Assignmenthelp.net provide homework, Assignment Help to the school, college or university level students. Our expert online tutors are available to help you in Gravity. Our service is focused on: time delivery, superior quality, creativity and originality.

**To submit physics Gravity assignment click here**.

Following are some of the areas in physics Gravitation which we provide help: