[Note from mentor: this post does not use the standard homework template because it was originally posted in one of the other forums. It was moved here when it became apparent that it is based on a homework-type exercise.] how do I resolve these componants to find the energy of the particle? since energy is not a vector how do i calculate the energy of a particle given x and y componants of momentum? do i simply take the magnitude to find the total momentum and use this to find the energy? thanks in advance for any suggestions!