The independent variables in Part I, the ones intentionally manipulated, are the .

The independent variable in Part II, the one that is intentionally manipulated, is the
.

The dependent variable for both Parts I and II, the one that you measure the response in, is the

The car would move to the right with 150 n of force. the 150 n of force from friction and air resistance slows the car from moving to the right with 300 n of force.

Ireally don’t know

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. 

It is the areas with lines. this may sound a little confusing, but i hope it !