What can be said about the displacement of Sally compared to the displacement of the cellular signal traveling in a geosynchronous orbit?

In the context of this question, understanding the nature of displacement for both Sally and the cellular signal is key. The cellular signal in a geosynchronous orbit travels around the Earth at a height where it can maintain a constant position relative to the Earth's surface, meaning it follows a circular path as the Earth rotates.

On the other hand, if Sally is situated on the surface of the Earth, her displacement would be determined by her position relative to some starting point as she moves.

The significant difference lies in the nature of their motion. While Sally may be moving through varying paths on the Earth's surface, the cellular signal typically moves straight to and from the satellite in a consistent directional path, effectively traveling vertically up to the satellite and then down to the Earth. Thus, if Sally is moving on the ground and the cellular signal's movement follows a direct vertical communication path, the displacements are indeed opposite to each other.

This means that even if we consider the magnitude of Sally's displacement as she moves horizontally, the cellular signal's displacement, which is dominated by its vertical travel to the satellite, would point in the opposite direction. Such a relationship highlights the nature of their respective paths, supporting the idea that their displacements can be viewed as oppositional