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# What is the part of the wave where the molecules are pressed together?

## What is the part of the wave where the molecules are pressed together?

Sound is a form of energy produced and transmitted by vibrating matter. Sound waves are compression (longitudinal) waves. As sound waves travel, molecules are pressed together in some parts (compression) and in some parts are spread out (rarefaction).

What happens to molecules when something vibrates?

When an object vibrates, it causes movement in surrounding air molecules. These molecules bump into the molecules close to them, causing them to vibrate as well. This makes them bump into more nearby air molecules. This “chain reaction” movement, called sound waves, keeps going until the molecules run out of energy.

### Can sound travel in a vacuum?

Sound waves are travelling vibrations of particles in media such as air, water or metal. So it stands to reason that they cannot travel through empty space, where there are no atoms or molecules to vibrate.

Do molecules really vibrate?

Molecules are made of atoms which are connected by chemical bonds. The length of the chemical bonds or the distance between atoms is not fixed. Hence, as a whole, molecules vibrate. Molecular vibration can be considered to be like the motion of particles connected by springs.

## What happens when two surfaces are pressed together?

Friction results from the two surfaces being pressed together closely, causing intermolecular attractive forces between the molecules of different surfaces. As such, friction depends upon the nature of the two surfaces and the degree to which they are pressed together.

What is the force between the floor and the box?

A static friction force exists between the surfaces of the floor and the box to prevent the box from being set into motion. The static friction force balances the force that you exert on the box such that the stationary box remains at rest.

### How is the tension force transmitted through a string?

The tension force is the force that is transmitted through a string, rope, cable or wire when it is pulled tight by forces acting from opposite ends. The tension force is directed along the length of the wire and pulls equally on the objects on the opposite ends of the wire.