when some one balance skate board on pipe the potential energy is responsible to make it slide beacause of m mass and g gravity and height thus the skate boarder concieves mgh potential energy and moving on pipe with balancing himself using kinetic enrgy ie;1/2 mv^2 and thus gauning speed ..for illustrating well there is a another example the two wheeeler gets balanced while moving instead of standing idle or stationary ie; kinetic energy is responsible for balancing