Question

As you move higher above the Earth's surface, that is, as altitude increases, how does the acceleration due to gravity (g) change?

Hint:

Gravity follows an inverse square law with distance from the Earth's centre.

Answer 1

The acceleration due to gravity decreases as altitude increases.

Step 1: Formula.
At a height h above the Earth's surface, gravity is given by \(g_h = g \left(\dfrac{R}{R+h}\right)^2\), where g is the value at the surface and R is the radius of the Earth.

Step 2: Explanation.
As h increases, the denominator \(R+h\) becomes larger than R, so the ratio \(\dfrac{R}{R+h}\) becomes smaller than 1. Squaring a number smaller than 1 makes it even smaller, so \(g_h\) becomes less than g.

Step 3: Physical reason.
Gravity follows an inverse square law with distance from the centre of the Earth. Moving to a greater height means moving farther from the centre of the Earth, so the gravitational pull weakens.

Step 4: Answer.
So the acceleration due to gravity decreases with increasing height above the Earth's surface.