Question

A body is projected with velocity V=3i+4j m/s. Then maximum height attained is what?

Answer 1

The first thing you need to decide is which unit vector points in the vertical direction. As far as I know, everyone in the known world uses i for the unit vector pointing in the positive x direction; j for the unit vector pointing in the positive y direction; and k for the unit vector pointing in the positive z direction.

You have two ways to approach this problem: consider using an equation of motion or consider using an energy analysis. Looking at the information you are given, which do you think might work best?