Why is gravitational potential energy negative?

Explanation

To understand why gravitational potential energy is negative, we can break it down into a few key steps:

### Step 1: Definition of Gravitational Potential Energy
Gravitational potential energy (U) is defined as the work done against the gravitational force to bring an object from a reference point (usually taken at infinity) to a specific point in a gravitational field.

### Step 2: Reference Point
In gravitational physics, we often take the reference point for potential energy at infinity, where the gravitational force is negligible. At this point, the gravitational potential energy is defined to be zero (U = 0).

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