You have observed a star and classified it as a red giant. It has a surface temperature of 3000 K and a luminosity of 105 times that of the Sun. Can you determine its mass by plotting its position on an H-R diagram?
A) Yes, its mass is 0.3 MSun.
B) Yes, its mass is 3 MSun.
C) Yes, its mass is 30 MSun.
D) No, a red giant's mass cannot be determined from its position on the H-R diagram.
D) No, a red giant's mass cannot be determined from its position on the H-R diagram.
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The energy source at the center of our galaxy
a. is not visible at optical wavelengths. b. produces X-rays. c. must be less than 10 AU in diameter. d. is not visible at optical wavelengths, produces X-rays, and must be less than 10 AU in diameter. e. None of the other choices are correct.
Flux: A rectangular loop of wire that can rotate about an axis through its center is placed between the poles of a magnet in a magnetic field with a strength of 0.40 T, as shown in the figure. The length of the loop L is 0.16 m and its width w is 0.040 m. What is the magnetic flux through the loop when the plane of the loop is parallel to the magnetic field?
A. 13 × 10-3 T ? m2 B. 2.6 × 103 T ? m2 C. 0.80 T ? m2 D. 2.6 × 10-3 T ? m2 E. 0 T ? m2
An important similarity that Newton noticed between a falling apple and the moon was that
A) the accelerations of both are toward the center of Earth. B) the net force on both is toward the center of Earth. C) Both of the above. D) the velocity of both is toward the center of Earth. E) All of the above.
How many basic units does the SI system have?
A) three B) four C) five D) seven E) ten