Posted by Jennifer on .
A motorboat is traveling 5m/s East, and encounters a current traveling 2.5m/s, North. If the witdth of the river is 80m wide, how much time does it take the boat to reach the other shore. I understand how to calculate the resulatant velocity, but I don't understand why you use the velocity 5 m/s to calculate the time and not the resultant velocity, 5.59m/s to calculate the time.

Physics 
bobpursley,
remember the displacement (with velocity) is a vector equation.
displacementEast=velocityEast*time