A pebble drops straight down into a tub of water, setting off ____________________ waves that travel at the boundary between the water and air.

circular waves

The type of waves that are set off when a pebble drops into a tub of water and travels at the boundary between the water and air are known as surface waves. Surface waves are commonly observed in bodies of water such as oceans, lakes, and even smaller bodies of water like bathtubs or tubs. These waves are distinctive because they travel along the surface of the water rather than propagating through the volume of the water like other types of waves.

To understand more about surface waves, let's take a closer look at how they are formed. When the pebble drops into the water, it creates a disturbance at the point of entry, causing water molecules to move and form circular ripples. These ripples then spread outwards from the disturbance in a concentric pattern, similar to the way ripples form when you drop a stone into a calm pond.

As the ripples propagate outward, they form surface waves that travel along the boundary between the water and air. These waves consist of two main components: transverse waves and longitudinal waves. Transverse waves cause the water's surface to move up and down perpendicular to the direction of wave propagation, while longitudinal waves create compressions and rarefactions in the water parallel to the direction of propagation.

The combined effect of these transverse and longitudinal waves results in the characteristic oscillations and undulations observed on the surface of the water. These surface waves gradually decrease in height and energy as they propagate away from the disturbance, eventually dissipating and becoming less noticeable.

In summary, when a pebble drops into a tub of water, it sets off surface waves that continuously travel along the boundary between the water and air, causing oscillations and undulations on the water's surface.