1. The problem statement, all variables and given/known data An object of mass m is dropped from a tower of height d. Show that according to quantum mechanics the closest the object can fall on average to the base of the tower is: (d/g)^(1/4) (h/m)^(1/2) 2. Relevant equations I don't know - that is the problem to know what to use. 3. The attempt at a solution Using v^2=u^2+ 2as => velocity when mass reaches ground is v=√2gd so momentum p=mv=m√2gd using Uncertainty Principle ∆x∆p=h => ∆x=h/∆p=h/(m√2gd) This is not the right answer so what have I done wrong?