Why did Hubble have to rely on Cepheids to find the distance to M31, unlike Shapley's use of RR Lyrae stars with the Milky Way?
What will be an ideal response?
The RR Lyrae stars were not bright enough to be seen from the distance of the Andromeda Galaxy, so Hubble used longer-period Cepheids in the spiral arms which were also much more luminous and showed up on his photos.
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The diagram below shows three approximate locations of the sun along the western horizon. Which number indicates the location of the sun at sunset on the vernal equinox for an observer at a latitude of 48° S?
a. 1
b. 2
c. 3
d. The sun will set in the east for an observer in the southern hemisphere.
e. The sun will not set on vernal equinox at this latitude.
What is the primary effect the carbon dioxide in Venus' atmosphere has on the planet?
What will be an ideal response?
In Bragg's law, 2d sin ? = m?, how is ? measured?
a. from the reflecting crystal plane b. from the normal to the reflecting crystal plane c. from the direction of the incident beam d. from the normal to the direction of the incident beam
A 10.0-kg object is initially moving with a velocity of 20.0 m/s to the north and is acted on by a constant net force. After the object moves 30.0 m to the north, its velocity is 12.0 m/s north
What is the constant net force acting on the object? A) 66.6 N north B) 3.33 N south C) 42.7 N south D) 214 N north E) 66.6 N south