The configuration factor between two infinitely long directly opposed parallel plates of finite width l is f1-2. the plates are separated by a distance d. (a) derive an expression for fi2 by integration of the configuration factor between parallel differential strip elements (b) derive an expression for f-2 by the crossed-string method

The answer which is not a detail carson used to describe the pool in the cave at low tide is b.  hundreds of periwinkles browse the branches and roots of the trees. 

You need to be more specific.  i really don't know what a "motion map" is.you can draw a graph of an object's position, distance, displacement, speed,velocity, or acceleration versus time, or you can draw a graph of the object's x-position versus its y-position and not give any information about time at all.if the graph presents position or displacement against time,  then constant velocity is a straight line . . i.e. a line that has  constant slope.if the graph shows speed against time, then constant velocityis a horizontal piece of line.if the graph shows acceleration against time, then constant  velocity is a piece of line that lies on the x-axis . . it's value is zero.