What will be happen, if the radius of Earth decreased, the value of gravitational acceleration on the surface of earth decrease or increase or will be same? And further what will be gravitational acceleration value at previous point lies on the surface of the when radius was not decreased? Explain, Gravity depends on the distance from the center or from the surface of the Body (of Earth).

4 minutes ago, SOHAN LAL YADAV said:

What will be happen, if the radius of Earth decreased, the value of gravitational acceleration on the surface of earth decrease or increase or will be same? And further what will be gravitational acceleration value at previous point lies on the surface of the when radius was not decreased? Explain, Gravity depends on the distance from the center or from the surface of the Body (of Earth).

If you suggest the radius decreases, do you mean the density increases, i.e. the mass remains constant, or do you mean the density stays constant and the mass decreases?

mass constant

The surface acceleration g = GM/R^2 so g increases as R decreases (G is Newton’s gravitational constant, R is the radius)

If R is halved, g will quadruple

Decreasing the radius of the Earth while keeping the mass unchanged will increase density and gravitational acceleration; this is termed gravitational collapse.

When the radius reaches R=2GM/c² we will have reached the Schwarzschild radius, where the gravitational acceleration is equivalent to the speed of light, and an Event Horizon is formed, resulting in a Black Hole.

This gravitational collapse cannot happen for a mass the size of the Earth; it only happens to stars about an order of magnitude more massive than our Sun, when these stars have exhausted their nuclear fuel, and radiation pressure cannot support against gravitational collapse.

But just for interest's sake, you would have to compress the Earth to a radius of about 9 mm ( give or take, as it would be spinning incredibly fast, so not true Schwarzschild ) to form a Black Hole from the Earth's mass.

Edited June 26Jun 26 by MigL

Just now, SOHAN LAL YADAV said:

What will be happen, if the radius of Earth decreased, the value of gravitational acceleration on the surface of earth decrease or increase or will be same? And further what will be gravitational acceleration value at previous point lies on the surface of the when radius was not decreased? Explain, Gravity depends on the distance from the center or from the surface of the Body (of Earth).

Please explain the purpose of your enquiry.

Is it for cosmology as has so far been assumed or the alternative geological hypothesis about plate tectonics being due to the Earth shrinking, or what ?