A crying baby emits sound with an intensity of 8.0 × 10-8 W/m2. Calculate a reasonable estimate for the intensity level from a set of quintuplets (five babies),
all crying simultaneously at the same place? The lowest detectable intensity is 1.0 × 10-12 W/m2.
A) 79 dB
B) 69 dB
C) 56 dB
D) 49 dB
E) 36 dB
C
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Constant Angular Acceleration: An old 78 rpm record rotates through an angle of 320° as it slows down uniformly from 78.0 rpm to 22.8 rpm. What is the magnitude of the angular acceleration of the record?
A. 2.34 rad/s2 B. 5.46 rad/s2 C. 6.50 rad/s2 D. 8.35 rad/s2 E. 10.9 rad/s2
Answer the following statement(s) true (T) or false (F)
1. At time t = 0 a person is sliding due east on a flat, frictionless plane of ice. The net force on this person is due to a battery-powered fan the person holds that exerts a southward thrust force on the person. Assuming that drag is negligible, the eastward component of the person’s velocity is unaffected by this force.
Every second, the Sun converts about 600 million tons of hydrogen into 596 million tons of helium. The remaining 4 million tons of mass is
A) ejected into space in a solar wind. B) ejected into space by solar flares. C) converted to an amount of energy equal to 4 million tons times the speed of light squared. D) reabsorbed as molecular hydrogen.
Why does neutron capture work?
A) Neutrons have no repulsive barrier to overcome in combining with positively charged nuclei. B) Neutrinos, because of their low mass and high speed, easily penetrate nuclei. C) Single protons have little repulsion to heavy nuclei and easily fuse with them. D) Photodisintegration makes many alpha particles, available for capture by nuclei. E) Neutronization captures all the protons and electrons.