Heavy water has a chemical formula d_2o. it is a form of water in which all hydrogen is deuterium ^2h and has a density of 1.11 g/cm^3. neglect the contribution of oxygen atoms. calculate the number of collisions required to slow down a neutron from 2 mev to 0.025 ev heavy water. determine the diffusion length of thermal neutrons in heavy water.

The answer is  a.first and third quarters 

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.