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Author Question: What is a galaxy's rotation curve? To which galaxies is it best applied, and what does it tell us ... (Read 66 times)

humphriesbr@me.com

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on: Jul 27, 2018
What is a galaxy's rotation curve? To which galaxies is it best applied, and what does it tell us about the distribution of dark matter?
 
  What will be an ideal response?

Question 2

When a spinning ice skater pulls in his arms, he spins faster because
 
  A) his angular momentum must be conserved, so reducing his radius must increase his speed of rotation.
  B) there is less friction with the air.
  C) there is less friction with the ice.
  D) there exists an unbalanced reaction force.


duy1981999

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Reply #1 on: Jul 27, 2018
Answer to Question 1

The speed of rotation at various distances from the galaxies center is plotted for spiral galaxies whose rotation is more easily observed. The flat curve going out toward the edge shows us that there must be a dark halo, extending well beyond the visible one, and that dark matter may account for 90 of the total mass.

Answer to Question 2

A


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