What is the speed of the ball just before it strikes the ground? use energy methods and ignore air resistance?

While we cannot calculate this balls particular speed, since we do not know from which height it fell or the weight of the ball. Speed, a scalar quantity, refers to how fast something is moving. In this case, we cannot estimate it's speed because we are lacking the balls physical dimensions. The balls velocity is a vector quantity and is defined as the rate at which an object changes it's position. Since most objects are bound by the physical law of terminal velocity, calculating the speed of the ball, in this case, is impossible without further information.