Amaterial with a cubic unit cell is heated from room temperature to 900°c without melting during this time, the bragg peaks in the x-ray diffraction pattern are seen to increase in width. the 20 position of the peak decreases over the same temperature range. explain these a) observations on an atomic scale. (note the mark allocation, there are 2 observations that need separate explanations)

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. 

I'd go for the one that says that knees are fulcrums, lower legs are levers and the ankles hold loads.hope it ,happy homework/ study/ exam!