Why do elliptical galaxies appear yellow or red?
A) They contain no hot, young blue stars
B) They contain only massive-stars that have progressed to the red-giant stage
C) They have very little dust or cool gas, and thus have little ongoing star formation
D) A and B
E) A and C
E
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Motional Emf: As shown in the figure, a straight wire carries a steady current I. A metal bar is in contact with a pair of rails and is in upward motion with velocity of magnitude ?. The polarity of the induced emf in terminals X and Y is
A. X and Y are at the same potential. B. X is positive and Y is negative. C. Y is positive and X is negative.
Two objects are at rest on a frictionless surface. Object 1 has a mass that is twice that of Object 2. When a constant force is applied to Object 1, it accelerates through a distance d. The force is removed from Object 1 and is then applied to Object 2. At the moment when Object 2 has accelerated through the same distance d, which statements are true?
(i) p2 = 2p1 (ii) p2 = p1 (iii) p2 = ½ p1 (iv) KE2 = 2KE1 (v) KE2 = KE1 (vi) KE2 = ½ KE1
1.(i) and (iv) 2.(ii) and (vi) 3.(i) and (v) 4.(iii) and (v)A 3.0 ? resistor is connected in parallel with a 6.0 ? resistor. This combination is connected in series with a 4.0 ? resistor. The resistors are connected to a 12. volt battery. How much power is dissipated in the 3.0 ? resistor?
A) 12 W B) 5.3 W C) 7.7 W D) 6 W E) 2.7 W
If the answer to your calculation has units of kg ? m2/s, what type of quantity could it be? (There could be more than one correct choice)
A) angular momentum B) power C) work D) force E) linear momentum F) torque G) rotational kinetic energy H) moment of inertia