The radii of two planets are R and 2R respectively and their densities p and `p"/"4` respectively. What is the ratio of acceleration due to gravity at their surfaces?

Explanation

To find the ratio of acceleration due to gravity at the surfaces of two planets with given radii and densities, we can follow these steps:

### Step 1: Understand the formula for acceleration due to gravity
The acceleration due to gravity \( g \) at the surface of a planet is given by the formula:
\[ g = \frac{G M}{R^2} \]
where \( G \) is the universal gravitational constant, \( M \) is the mass of the planet, and \( R \) is the radius of the planet.
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