Answer:
zero
Step-by-step explanation:
The gravitational force between two masses is jointly proportional to the masses and inversely proportional to the square of the distance between them. The constant of proportionality is the universal gravitational constant.
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In this scenario, the force to the right is matched by an identical force to the left from an identical mass at an identical distance. The magnitudes of the forces are equal, and their directions are opposite. The forces cancel.
The net force on the 2.2 kg mass in the center is zero.