velocity Force A dx y For solids dx is constant and is a function of F/A and y For liquids dx changes with time and a resulting velocity of The upper plane is a result. The velocity is constant and is a function F/A and yy Force A dx velocity For solids dx is constant and is a function of F/A and y For liquids dx changes with time and a resulting velocity of The upper plane is a result. The velocity is constant and is a function F/A and y