A champion athlete can produce one horsepower (746 W) for a short period of time. If a 70-kg athlete were to bicycle to the summit of a 500-m high mountain while expending power at this rate, she would have used at least ____ J of energy.
A. 746
B. 3.43 × 105
C. 3.73 × 105
D. 7.46 × 105
E. 2.61 × 107
Answer: B
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A semiconductor with an electrical conductivity of 300 (?·m)-1 at room temperature is produced by doping Group IV silicon with Group V antimony. Assume that the mobility of electrons in silicon is equal to 0.10 m2 /V·s and that the mobility of holes is equal to 0.001 m2 /V·s. You can assume that this semiconductor is in the extrinsic range of operation at this temperature.
(a) What type of semiconductor is this? (b) What doping concentration of antimony in atoms/m3 is necessary for this electrical conductivity? (c) State clearly any assumptions you make in this calculation.
A sound source of 100 watts radiates sound uniformly in all directions. The intensity of the sound at a distance of 4.00 m is
A. 0.301 
B. 0.353
C. 0.497
D. 0.535
E. 0.621
An astronaut weighs 99 N on the Moon, where the acceleration of objects due to the gravitational attraction is 1.62 m/s2. How much does she weigh on Earth?
A) 16 N B) 61 N C) 99 N D) 600 N E) 440 N
A coil with a self-inductance of 6 H has a constant current of 2 A flowing through it for 2 seconds. What is the emf induced in this coil?
A) 6 V B) 12 V C) 0 V D) 4 V E) 8 V