Hello everyone,

Today I saw some waves in my physics lessons. A stone drops into water, and waves are created and spread from source to surroundings. Finally, the water became calm again.

What's the most proper explanation for that?

 

I think: Water molecules gain energy after being hitting, they collide the others.

By law of conservation of momentum, it is rather obvious to see the total amount of kinetic energy decreases after a collision. Finally, it becomes 0.

Is my explanation correct?

I think your explanation is right, but just to give you another point of view, I'll give you mine.

 

Water is an elastic system, do you agree??? It's particles are bond to each other by a conservative force, which is the electromagnetic interaction, so, if the system is deformed by an external force, eg: a rock falling into the water and facing it's surface tension, the system gains potential energy.

 

Because the system is elastic, this potenetial energy transforms into kinetic energy as the system attempts to get back to equilibrium in a less energetic state, as it was before. This is what we call Simple Harmonic Movement: a restaurating conservative force attempting to bring the deformed system back to the state of less energy possible.

 

Now, the water waves stop oscillating because they are inside a dissipative media, and energy is lost as the surface of water collides with air particles, and suffer many other losses of energy.

 

I hope my explanation was satisfying, but if not, just let me know.

 

David Angel R. Tijerina

Universidad Autónoma de Nuevo León, México

Faculty of Physical and Mathematical Sciences

Undergrad

water wave can be longitudinal, right?