1. The problem statement, all variables and given/known data Grains of sand of mass 2.90x10^-3 g each, fall from a height of 0.5 m on a sticky surface at a rate of 45 grains per second per cm^2. What pressure does this shower of sand exert on the surface, assuming that air resistance can be neglected? 2. Relevant equations p=F/A=mv^2(N/V) 3. The attempt at a solution I don't know where to start. Anyone care to point me in the right direction?