1. what occurs as the convection current moves toward the upper mantle
density increases
density decreases
temperature increases
temperature decreases
2. what occurs as the convection current moves toward the lower mantle
(same options as #1)
I think the answer is decreased and increased temperature.
1. As the convection current moves toward the upper mantle, the correct answer is: density increases.
To understand why density increases, we can look at the process of convection in Earth's mantle. Convection occurs due to the transfer of heat energy through the movement of a fluid. In this case, the fluid is the mantle material. As heat is transported from the lower mantle to the upper mantle, it causes the mantle material to heat up, expanding and becoming less dense.
When the material reaches the upper mantle, it starts to cool down. As it cools, it contracts and becomes denser. The denser material then sinks back towards the lower mantle, completing the convection cycle. So, as the convection current moves toward the upper mantle, density increases.
2. As the convection current moves toward the lower mantle, the correct answer is: density decreases.
When the material reaches the upper mantle and cools down, it becomes denser and starts to sink back towards the lower mantle. As it descends, it encounters higher temperatures and pressure, causing it to heat up and expand. This expansion results in a decrease in density, allowing the material to rise again towards the upper mantle.
This continuous cycle of heating, expansion, rising, cooling, and sinking creates the convection currents in the mantle, which play a significant role in driving the movement of Earth's tectonic plates.