Final answer:
Toothpaste resembles Earth's asthenosphere in that it behaves both like a solid and a liquid - it holds shape when pressured and flows when pressure is applied, similar to the asthenosphere's semi-solid state and ability to flow under the tectonic plates.
Step-by-step explanation:
The question asks how toothpaste is like Earth's asthenosphere. The similarity lies in the fact that toothpaste can behave both like a solid and a liquid. When in the tube under pressure, it holds its shape much like Earth's asthenosphere, which is semi-solid under high pressure.
However, when you apply toothpaste to a toothbrush, it flows easily, similar to the asthenosphere which can flow as the tectonic plates move on top of it. This state is due to the asthenosphere being partially molten and behaving plastically under strain, like toothpaste flowing out of the tube when squeezed.
Moreover, Earth's tectonic plates that rest on the asthenosphere are moved by convection currents, much like how the squeezing of a toothpaste tube propels the toothpaste forward. Both the asthenosphere and toothpaste exhibit properties that allow them to change state under various conditions, which is a result of their physical characteristics.
Toothpaste is composed of abrasives like calcium carbonate and detergents that give it the ability to clean teeth, while it also contains flavorants and remineralizers for pleasant taste and tooth enamel restoration. Similarly, the Earth's asthenosphere, lying beneath the lithosphere, has physical properties that enable the movement of tectonic plates, influencing the surface activity of Earth, like earthquakes and the formation of mountain ranges.