Which velocity component to use in kinetic energy with projectile motion?

[rygza]

When do i know which component of velocity to use when an object is shot at an angle?

For example: a ball of given mass is shot 32degrees above the ground with Vinitial of 74m/s. In using conservation of energy, K.E. = .5 mv^2 , which velocity component do i use?

 

[gneill]

KE is a scalar. Use the magnitude of the velocity vector (i.e., both components contribute to the total KE).

 

[ashishsinghal]

in conservation of energy you take net velocity