A machine puts out 100 watts of power for every 1000 watts put into it. The efficiency of the machine is
A) 10%.
B) 50%.
C) 90%.
D) 110%.
E) none of the above
Answer: A
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In a series LRC circuit the rms voltage across the resistor is 80 V, across the capacitor is 120 V, and across the inductor is 60 V. What is the phase constant for this circuit?
A. 27
B. -27
C. 37
D. -37
E. -41
The graph below plots the escape velocity of each planet along the vertical axis and its surface temperature along the horizontal. The lines plotted in the figure are the average speeds of gas particles as a function of temperature for various gases. Which of the planets or satellite plotted in this diagram is least able to hold an atmosphere?
Ideal Gas Law: A 0.40-m3 gas tank holds 7.0 moles of ideal diatomic nitrogen gas at a temperature of 290 K. The atomic mass of nitrogen is 14.0 g/mol. What is the pressure of the gas? (R = 8.31 J/mol ? K, 1 atm = 101 kPa)
A. 42 atm B. 37 atm C. 32 atm D. 27 atm E. 22 atm
What do moonquakes reveal about the Moon?
A) It has a strong magnetic field generated by a large molten core. B) It has a differentiated core, displaced away from us by the Moon's rotation. C) Its small, partially molten core has been pulled toward us by tidal forces. D) The Moon has been geologically dead throughout its entire history. E) The Moon is quite active, almost as much so as Jupiter's moon Io.