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.
Sound waves are just vibrations of molecules, so the molecules or particles in a solid vibrate transversely. Sound also travels faster in solids, 5000m/s in steel, while only â¦ 300m/s in air. This is because the particles are closer together meaning the energy has less of a distance to travel between the particles.