Among the wavelengths emitted by iron atoms are λ = 500.572 nm and λ = 500.613 nm. if we want to separate these two wavelengths clearly in the first order spectrum of a diffraction grating, what is the minimum number of lines that are required? if the spectral lines are observed in the second order spectrum also, calculate the number of lines required in this case.

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. 

Wow good luck with that answer