Question

At what height above the earth's surface the acceleration due to gravity will be 19 of its value at the earth's surface

Answer 1

The acceleration due to gravity is inversely proportional to the square of radius. So the acceleration due to gravity will decrease as we go higher.

The formula of acceleration due to gravity

g=GM/r^2

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

So half it's value is 4.9m/s^2

By putting the values in the formula.

The final ans is approx 9038km from centre

So above the earth's surface it's is

9038–6400=2638km(approx)

So acceleration due to gravity decreases by half at an height of 2638km.(approx)