Box 1 of mass m is on a flat floor and accelerated from rest by a constant net force F over a distance x. The force F ceases to act at the instant block 1 collides with and sticks to box 2, which is initially at rest and made of the same material. The boxes have a total mass M and slide a distance D before coming to rest due to the effects of friction, where the coefficient of kinetic friction is µ. Professor Jovannee Lowfield suggests that the distance D is given by the equation above. Name all aspects of this equation that are implausible.