A heat conducting rod, 1.40 m long, is made of an aluminum section that is 0.50 m long and a copper section that is long. Both sections have cross-sectional areas of
The aluminum end and the copper end are maintained at temperatures of and respectively. The thermal conductivity of aluminum is 205 W/m ? K of copper is 385 W/m ? K. The rate at which heat is conducted in the rod is closest to
A) 20 W.
B) 18 W.
C) 23 W.
D) 25 W.
E) 28 W.
Answer: A
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In the geometric analogy, the coordinate time difference ?t between two events in space time corresponds to
A. The north–south separation between points on a plane. B. The distance between points on a plane. C. A certain path length between points on a plane. D. The separation between the events in space time. E. Something else (specify).
An optic fiber is made of clear plastic with an index of refraction of 1.50. For what range of angles of incidence ? with the lateral surface of the fiber will light remain inside the plastic "guide" if it is surrounded by air?
A) 21.1° < ? < 90° B) 23.4° < ? < 90° C) 38.3° < ? < 90° D) 40.3° < ? < 90° E) 41.8° < ? < 90°
An ideal gas is taken around the process shown. The net work done on the gas is most nearly:
A 50.0-N box is sliding on a rough horizontal floor, and the only horizontal force acting on it is friction. You observe that at one instant the box is sliding to the right at 1.75 m/s and that it stops in 2.25 s with uniform acceleration
What magnitude force does friction exert on this box? A) 3.97 N B) 8.93 N C) 38.9 N D) 50.0 N E) 490 N