Calculate the time it takes for the rock to reach its maximum height. A. 1.50 seconds
B. 2.47 seconds
C. 3.00 seconds
D. 4.94 seconds

Velocity is the speed of an object in a certain direction so you'd need to know speed and direction

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. 

Two 10¢  coins  (dimes)  carrying identical charges  are  lying 2.5 m apart  on a  table.  if each  of  these coins experiences  an  electrostatic force  of  magnitude 2.0 n due  to the  other coin.  the charge on each coin is :     52.2 uc