If we observe one edge of a planet to be redshifted and the opposite edge to be blueshifted, what can we conclude about the planet?
A) The planet is rotating.
B) We must actually be observing moons orbiting the planet in opposite directions, not the planet itself.
C) The planet is in the process of falling apart.
D) The planet is in the process of formation.
A) The planet is rotating.
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Rotational Dynamics: A uniform rod is 2.0 m long. It is hinged to a wall at its left end, and held in a horizontal position at its right end by a vertical very light string, as shown in the figure. What is the angular acceleration of the rod at the moment after the string is released if there is no friction in the hinge?
A. 15 rad/s2 B. 3.3 rad/s2 C. 7.4 rad/s2 D. 11 rad/s2 E. It cannot be calculated without knowing the mass of the rod.
At extremely high temperatures (e.g., millions of degrees), which of the following best describes the phase of matter?
A) a gas of rapidly moving molecules B) a plasma consisting of positively charged ions and free electrons C) a gas consisting of individual, neutral atoms, but no molecules D) a plasma consisting of rapidly moving, neutral atoms E) none of the above (At these extremely high temperatures, matter cannot exist.)
A seed is 15 mm in front of a convex lens, and the image of the seed is 4.0 mm behind the lens. What is the focal length of the lens?
A) 11 mm B) 5.5 mm C) 3.8 mm D) 3.2 mm
Identical point charges Q are placed at each of the four corners of a 3.0-m × 4.0-m rectangle. If Q = 40 ?C, what is the magnitude of the electrostatic force on any one of the charges?
a. 3.0 N b. 2.4 N c. 1.8 N d. 3.7 N e. 2.0 N