Since the rate of heat transfer by conduction is proportional to the ?T, what percent savings in your heating bill would you expect if you turned the thermostat down from 75° to 65°F, and the outside temperature is 25°F?
a. 10% b. 20% c. 30% d. 40% e. 50%
b
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If you were to inhale a few breaths from a helium gas balloon, you would probably experience an amusing change in your voice. You would sound like Donald Duck or Alvin the Chipmunk. What is the cause of this curious high-pitched effect?
A) The helium causes your vocal cords to tighten and vibrate at a higher frequency. B) For a given frequency of vibration of your vocal cords, the wavelength of sound is less in helium than it is in air. C) Your voice box is resonating at the second harmonic, rather than at the fundamental frequency. D) Low frequencies are absorbed in helium gas, leaving the high frequency components, which result in the high, squeaky sound. E) Sound travels faster in helium than in air at a given temperature.
Which kind of robotic space mission enables us to take a quick look at a planet?
A) sample return B) flyby C) orbiter D) lander/probe
Shepherd satellites keep Saturn's F ring narrow
Indicate whether the statement is true or false
The diagram below shows the position of a long straight wire perpendicular to the page and a set of directions labeled A through H. When the current in the wire is directed up out of the page, the direction of the magnetic field at point P is
A. E. B. F. C. G. D. H. E. A.