The primary responsibilities of human resources are: 1  C - Compensation. 2  H - Human resource development. 3  E - Employee and labor relations. 4  S - Safety and health. 5  S - Staff.
A new technique uses sound waves to levitate objects and move them in mid-air. Credit: Dimos Poulikakos View full size image. View full size image. Hold on to your wand, Harry Potter: Science has outdone even your best Leviosa! levitation spell.
1 A sound wave is a mechanical wave. 2  A sound wave is a means of transporting energy without transporting matter. 3  Sound can travel through a vacuum.  A sound wave is a pressure wave; they can be thought of as fluctuations in pressure with respect to time.