In a photo like the Hubble eXtreme Deep Field (Figure 20.1 in your text), we see galaxies in many different stages of their lives. In general, which galaxies are seen in the earliest (youngest) stages of their lives?
A) the galaxies that are farthest away
B) the galaxies that have the most hot, young stars of spectral types O and B
C) the galaxies that are the reddest in color
D) the galaxies that are nearest to us
A) the galaxies that are farthest away
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Where would you most likely find a large radio telescope?
a. in a busy, populated area b. at the peak of a mountain c. on top of a tall building d. in a mountain valley e. near multiple radio towers
Magnetic Field of a Current Loop: A flat circular coil having 57 turns of very thin wire has a diameter of 9.5 cm and carries 7.2 A of current. (?0 = 4? × 10-7 T ? m/A)(a) What is the strength of the magnetic field at the center of the coil?(b) If the same length of wire were used to make a coil with twice the original diameter, how large would the magnetic field at the center be when it carried the same current as before?
What will be an ideal response?
The lower the frequency of a sound wave, the
A) lower its velocity. B) greater its wavelength. C) smaller its amplitude. D) shorter its period. E) greater its velocity.
A catapult is tested by Roman legionnaires. They tabulate the results in a papyrus and 2000 years later the archaeological team reads (distances translated into modern units): Range = 0.20 km; angle of launch = ?/4; landing height = launch height
What is the initial velocity of launch of the boulders if air resistance is negligible? A) 44 m/s B) 1.4 m/s C) 22 m/s D) 0.69 m/s