Question

Circular water wavCircular water waves decrease in amplitude as they move away from where a rock is dropped. Explain why.es decrease in amplitude as they move away from where a rock is dropped. Explain why.

Short answer

The energy of the circular waves created in water keeps on decreasing as the water molecules along the waves keeps on interacting with each other and as a result amplitude of wave decreases.

Step-by-step solution

Description of circular water waves

When a rock is dropped at a point in a standing wave, it creates disturbance in the water at that point. This disturbance is then propagated radially outwards in all directions in the form of circular waves.

Energy in circular water waves

When a rock with a kinetic energy touches the water, the kinetic energy gets converted into wave motion. As the wave propagate radially, the water molecules on the surface of water produces friction (known as viscosity) while interacting with the molecules inside the surface of water. As a result the energy in the wave motion start getting absorbed by the water molecules as they move away from the point of impact of the rock.

Relation between energy of wave motion and amplitude

Wave’s energy is directly proportional to the square of its amplitude.Hence if the energy of wave motion decreases, its amplitude will also decrease in the process.

That is why circularwater waves decrease in amplitude as they move away from where a rock is dropped.