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.
The key background to this question is the nature of sound waves and light waves. Youâre right in that sound waves are a vibration traveling through an object, including condensed things like solids and liquids. In solids, those waves can consist of either alternating compressed and stretched regions, or regions wiggling sideways, compared to the direction the wave is traveling.