A mysterious force has been discovered in nature that acts on all particles in the three-dimensional space. You determine that the force is always pointed away from a definite point in space, which we can call the force center. The magnitude of the force turns out to be proportional to 1/r4, where r is the distance from the force center to any other point. Your friend says that it has been determined that the constant of proportionality has been determined to be 2 (in units to be determined), i. e. the magnitude of the force on a particle can be written as 2/r4, when the particle is at a distance r from the force center.