1. The problem statement, all variables and given/known data We have a heavy chain with length of L and weight of m placed on a table. we take an end of it and move it with constant velocity of v upwards. so each moment it gets heavier. If the force needed for this uniform speed is called F, and length of chain which is higher than the table is called y, write F as a function of y. 2. Relevant equations F=ma y=vt 3. The attempt at a solution equation of chain's weight at each moment is [tex]M=ym/L=vtm/L[/tex] and delta M is equal to [tex]\delta M=vm/L[/tex] But I can't calculate the force needed to make this motion with uniform speed.