Question

A mysterious force acts on all particles along a particular line and always points towards a particular point P on the line. The magnitude of the force on a particle increases as the cube of the distance from that point, that is, F∝ r3, if the distance from the P to the position of the particle is r. It has been determined that the constant of proportionality is 0.99 N/m3, i.e. the magnitude of the force on a particle can be written as 0.99r3, when the particle is at a distance r from the force center.