Jadeen says that you can increase the resistance of a copper wire by hammering the wire to make it narrower and longer. Arnell says that you can increase its resistance by heating the wire. Which one, if either, is correct, and why?
a. Arnell, because the resistivity of the wire increases when it is heated.
b. Arnell, because the resistivity of the wire decreases when it is heated.
c. Jadeen, because the resistivity of a wire is inversely proportional to its area and directly proportional to its length.
d. Jadeen, because the resistivity of a copper wire does not decrease when it is hammered.
e. Both are correct because (a) and (d) are both correct.
e
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Which of the following describes a major danger of interstellar travel at near-light speed?
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The reason that you do not observe a Doppler shift when you listen to the car radio while driving is that
A) the source and observer are moving at the same speed. B) the air inside the car is moving at the same speed as the car. C) the speed of the car is too slow compared to the speed of sound. D) the speed of the car is too fast compared to the speed of sound. E) there is a Doppler shift but we don't notice it.
Calculate the total entropy change that occurs when 2.00 kg of lead at 40.0°C are placed in a very large quantity of water at 10.0°C. The specific heat of lead is 0.031 cal/(g?K)
A) 190 J/K B) 100 J/K C) 6.6 J/K D) 6.2 J/K E) 1.4 J/K