Tell me a little bit about extinct volcanoes

it in science

When a volcano makes the news for erupting, you’ll often hear mention of other kinds of volcanoes that are dormant or extinct. But what do those terms mean, exactly, and how do scientists figure that out?

First, a little bit about how volcanoes work: Magma collects in reservoirs beneath the earth’s surface, and as it accumulates, pressure in the chamber increases; if it gets high enough, the rocks over it will break, and an eruption will ensue. The silica content of the magma determines what kind of volcano you’ll have. Low silica magma makes shield volcanoes, like Kīlauea on Hawaii’s big island, and cinder cones, like Mexico’s Paricutín, which have lava that flows easily, like molasses. High silica magma creates stratovolcanoes, like Mount St. Helens in Washington, and calderas like the one under Yellowstone National Park, which have lava that is more viscous and flows like taffy.

one person pulls 90n one way and the other has 100n pulling the other way.

so the net force = 90 - 100 = -10n,

or the ans can be 10n if the picture shows -90n and 100n instead.