Magnetic Field of a Long Wire: A long straight wire has a constant current flowing to the right. A rectangular metal loop is situated above the wire, and also has a constant current flowing through it, as shown in the figure. Which one of the following statements is true? 
A. The net magnetic force on the rectangle is upward, and there is also a nonzero torque on the rectangle.
B. The net magnetic force on the rectangle is zero, and the net torque on it is zero.
C. The net magnetic force on the rectangle is downward, and there is also a nonzero torque on the rectangle.
D. The net magnetic force on the rectangle is zero, but there is a nonzero torque on the rectangle.
E. The net magnetic force on the rectangle is downward, and the net torque on it is zero.
Answer: E
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One mole of an ideal gas has a temperature of 25°C. If the volume is held constant and the pressure is doubled, the final temperature (in °C) will be
A. 174 B. 596 C. 50 D. 323 E. 25
A cooling system is to be designed for a food storage warehouse for keeping perishable foods cool prior to transportation to grocery stores. The warehouse has an effective surface area of 1860 m2 exposed to an ambient air temperature of 320C. The warehouse wall insulation (k = 0.17 W/(m K)) is 7.5 cm thick. Determine the rate at which heat must be removed (W) from the warehouse to maintain the food at 4°C.
GIVEN
• Cooled warehouse
• Effective area (A) = 1860 m2
• Temperatures
? Outside air = 32°C
? food inside = 4°C
• Thickness of wall insulation (L) = 7.5 cm = 0.075 m
• Thermal conductivity of insulation (k) = 0.17 W/(m K)
FIND
• Rate at which heat must be removed (q)
ASSUMPTIONS
• One dimensional, steady state heat flow
• The food and the air inside the warehouse are at the same temperature
• The thermal resistance of the wall is approximately equal to the thermal resistance of the wall insulation alone
SKETCH
The ________ star clusters are younger, and their stars richer in heavier elements released in supernova events
Fill in the blank(s) with correct word
Which of the following is not expected for a "hot Jupiter" that orbits 0.05 AU from its star?
A) cloudtop temperatures over 1000 K B) intense volcanism C) clouds made of rock dust D) density similar to or lower than Jupiter's