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.
Both the waves in the flag and the ocean waves are waves that you can see. There are other kinds of waves. We cannot see these waves, but we experience them every day. These waves are called electromagnetic waves. Sound is also a type of wave that we cannot see. Like ocean waves, sound waves something to travel through like waves through the ocean or through a flag. Sound can travel through air because air is made of molecules. These molecules carry the sound waves by bumping into each other, like dominoes knocking each other over.