Sound waves in the interstellar medium
A) travel so slowly that they are undetectable.
B) travel extremely quickly and are therefore very loud.
C) can travel through the halo interstellar medium but not the disk of the galaxy.
D) can travel through the gas, but the very low density of the interstellar medium makes them inaudible.
E) cannot travel through the gas.
D
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A steel rod (Es 5 210 GPa, dr 5 12 mm, ctes 5 12 3 1026/°C) is held stress-free between rigid walls by a clevis and pin (dp 5 15 mm) assembly at each end. If the allowable shear stress in the pin is 45 MPa and the allowable normal stress in the rod is 70 MPa, the maximum permissible temperature drop ?T is approximately:
(A) 14 8C
(B) 20 8C
(C) 28 8C
(D) 40 8C
The circuit below contains three 100-W light bulbs and a capacitor. The emf ? = 110V. At the instant the switch S is closed, which light bulb is brightest?
a.
A
b.
B
c.
C
d.
A and B
e.
All three are equally bright.
A 120 N picture hangs from a nail in the wall. The maximum shear stress the nail can sustain is 1.00 
The smallest diameter the nail can be is
A. 10.5 mm. B. 12.4 mm. C. 13.7 mm. D. 14.4 mm. E. 15.9 mm.
For hydrogen, the transition from the first to third excited state produces
A) an infrared line. B) an ultraviolet line. C) a red emission line. D) a blue green absorption line. E) a violet emission line.