Question

Which of the following statements about red giant stars are true? (Select all that apply.)

		Red giant stars are less luminous than main sequence stars of the same temperature.
		Red giant stars tend to be more luminous than main sequence stars of the same temperatures because they are larger in size.
		Red giant stars are less luminous than main sequence stars because fusion happens more rapidly in main sequence stars.
		A red giant star of a given temperature is more luminous than a main sequence star with the same temperature.

Which of the following statements about white dwarf stars are true? (Select all that apply.)

		White dwarfs are extremely luminous because they are so hot and dense.
		The luminosity of a white dwarf does not depend on its temperature.
		White dwarfs are fainter than main sequence stars because they are much smaller in size.
		White dwarfs are not supported by gas pressure, but by quantum pressure - also called electron degeneracy pressure.

1. Does the following passage describe a positive or negative feedback loop (or neither)?

   When you select a genre of music to listen to on your music streaming app, the app records data about how long you listen to that genre. The more you listen to a genre, the more likely the app is to recommend music of that genre. A recommendation by the app will make you more likely to continue to listen to that genre, which will then influence future recommendations.

   		Positive
   		Negative
   		Neither

2. Which of the statements below are true regarding how feedback loops govern the fusion process in main sequence stars? (Select all that apply.)

   		If the temperature in the core of a star increases due to an increase in the rate of fusion, a negative feedback loop causes the star to cool back down.
   		If the temperature in the core of a star increases due to an increase in the rate of fusion, a positive feedback loop causes the star to continue to heat up.
   		If the temperature in the core of a star decreases due to a decrease in the rate of fusion, a positive feedback loop causes the star to continue to cool down.
   		If the temperature in the core of a star decreases due to a decrease in the rate of fusion, a negative feedback loop causes the star to heat back up.

Answer 1

According to the Stefan-Boltzmann Law: L = 4 R2 T4 For same temperature T, larger red giant stars with larger radius R will be more luminous (L). Correct choices- Red giant stars tend to be more luminous than main sequence stars of the same temperatures because they are larger in size. A red giant star of a given temperature is more luminous than a main sequence star with the same temperature.

2. Correct choices-White dwarfs are fainter than main sequence stars because they are much smaller in size.

White dwarfs are not supported by gas pressure, but by quantum pressure - also called electron degeneracy pressure. (Because electron degeneracy pressure stops the gravitational collapse of dying stars and forms White dwarfs.)

3. A recommendation by the app will make you more likely to continue to listen to that genre, that’s a positive loop, as in future, app will recommend the music from same genre.
4. Stars are balanced because they have negative loop.

Correct choices-If the temperature in the core of a star increases due to an increase in the rate of fusion, a negative feedback loop causes the star to cool back down.

If the temperature in the core of a star decreases due to a decrease in the rate of fusion, a negative feedback loop causes the star to heat back up.