In an operating electrical circuit the source of potential difference could be

In an operating electrical circuit, the source of potential difference is called the energy source, where current flows from the higher potential to the lower potential. The unit of electrical potentials is known as voltage.

Explanation:

As the charging carriers pass through them, the energy is passed to the electrical components inside a circuit. To measure the potential difference we use a voltmeter.The difference in potential is equal to the sum of current multiplied by the resistance. The potential difference of one volt is equal to one Joule of energy used by one Charging Coulomb as it flows in a circuit between two points.

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.