Abox rests on the (frictionless) bed of a truck. the truck

driver starts the truck and accelerates forward. the box!

immediately starts to slide toward the rear of the truck

bed. discuss the motion of the box, in terms of newton's

laws, as seen (a) by mary standing on the ground beside

the truck, and (b) by chris who is riding on the truck

(fig. 4–35).

Ibelieve the answer you're looking for is

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. 

The independent variable in this experiment is the angle at which the light from the ray box strikes the mirror.hope this .