Only type O stars are hot enough to show ionized ________ in their spectra
Fill in the blank(s) with correct word
helium
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An object is 10 cm in front of a concave spherical mirror with a focal length of magnitude 3.0 cm. Where is the image?
A) 13 cm from the mirror B) 7.0 cm from the mirror C) 4.3 cm from the mirror D) 3.3 cm from the mirror
A nonuniform 2.0-kg rod is 2.0 m long. The rod is mounted to rotate freely about a horizontal axis perpendicular to the rod that passes through one end of the rod. The moment of inertia of the rod about this axis is 4.0 kg×m2 . The center of mass of the rod is 1.2 m from the axis. If the rod is released from rest in the horizontal position, what is its angular speed as it swings through the
vertical position? a. 3.4 rad/s b. 4.4 rad/s c. 4.3 rad/s d. 5.8 rad/s e. 6.8 rad/s
Percival Lowell’s claims of a Martian civilization generated great public interest, but other scientists of his time were highly skeptical of these claims. Which two of the following statements (which are all true) explain why other scientists of the late 19th and early 20th centuries rejected Lowell’s claims?
a. Lowell’s canals did not appear in photographs of Mars taken through telescopes. b. Lowell’s canals followed perfectly straight lines for thousands of kilometers. c. Mars has an axis tilt very similar to Earth’s axis tilt. d. Like Earth, Mars has polar ice caps. e. Mars rotates with a period only a little longer than Earth’s rotation period.
The graphs below show angular velocity as a function of time. In which one is the magnitude of the angular acceleration constantly decreasing?
A.
B.
C.
D.
E.
