Intensity of Sound: The intensity level is 65 dB at a distance 5.00 m from a barking dog. What would be a reasonable estimate for the intensity level if two identical dogs very close to each other were barking? You can ignore any interference effects.
A. 65 dB
B. 68 dB
C. 130 dB
D. 136 dB
Answer: B
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A rectangular box of negligible mass measures 5.0 m long, 1.0 m wide, and 0.50 m high. How many kilograms of material can be loaded onto the box before it sinks in a lake having water of density 1000 kg/m3?
A) 0.50 × 103 kg B) 1.5 × 103 kg C) 2.5 × 103 kg D) 3.5 × 103 kg
Which of the following is not a strong argument for the theory that some large elliptical galaxies formed as the result of galaxy collisions?
A) Elliptical galaxies dominate the population in dense galaxy clusters. B) Some ellipticals have stars and gas that rotate opposite to the rest of the galaxy. C) Some elliptical galaxies are surrounded by shells of stars. D) Computer simulations predict that the product of a galaxy collision is generally an elliptical galaxy. E) Galaxy collisions are common and most galaxies in the universe are elliptical.
You would expect millisecond pulsars to be
A) isolated in space. B) part of a binary system. C) most common in open clusters. D) collapsing rapidly. E) rotating slowly.
What is true of a blackbody?
A) If its temperature doubled, the peak in its radiation curve would be doubled in wavelength. B) Its energy peaks at the wavelength determined by its temperature. C) It has a complete absence of thermal energy. D) Its energy is not a continuum. E) It appears black to us, regardless of its temperature.