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.
This seems like a straightforward question with straightforward answer, but all may not be what it seems. That said, the science is straightforward: A sound wave is a transfer of energy as it travels away from a vibrating source. Sound waves are formed when a vibrating object causes the surrounding medium to vibrate.