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Difficulty: MediumStars, Galaxies, and the Universe

Complete the statement regarding the physical forces governing stellar stability during a star's main sequence. What terms correctly fill in each blank?

Answer:A main-sequence star maintains structural stability when the inward compression caused by 【gravity】 is balanced by outward thermal pressure from nuclear fusion, creating a state known as 【hydrostatic】 equilibrium.

Answer

gravity (or gravitational force) for the first blank, and hydrostatic for the second blank
During the main sequence phase of a star's life, the tremendous inward pull of gravity is exactly matched by the outward thermal and radiation pressure generated by hydrogen fusion in the core. This balanced state is called hydrostatic equilibrium, allowing the star to maintain a constant size and luminosity for billions of years.

Step-by-Step Solution

1
Identify the inward compressive force acting on a star's mass.
Gravity pulls all stellar matter toward the center of the star.
Massive celestial bodies generate immense gravitational attraction directed inward toward the core.
2
Identify the scientific term for the precise balance between inward gravity and outward thermal/radiation pressure.
The balance is defined as hydrostatic equilibrium.
Hydrostatic equilibrium is the defining physical condition that prevents a main-sequence star from either collapsing under its own gravity or blowing itself apart from internal fusion pressure.

Key Concept

Hydrostatic equilibrium and stellar stability
Estimated Time:45s
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Topics

Stars, Galaxies, and the Universe

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