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.
When something vibrates (like your voice box) it causes the molecules around it to also vibrate, which then causes a ripple of motion (known as a sound wave) that can travel through air, water, and solid materials such as wood or a piece of string.e hear sounds because the vibrations created travel through the air to our ears. Notice that when people want to hear something better they often cup their hand around their ear. This is to help them catch the sound waves.