The decibel level of sound is related to its
A) wavelength.
B) intensity.
C) velocity.
D) frequency.
E) pitch.
B
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When a hunter fires a rifle, the hunter feels a force against her shoulder. Explain why
What will be an ideal response?
A 2.54-cm-OD, 1.9-cm-ID steel pipe carries dry air at a velocity of 7.6 m/s and a temperature of –7°C. Ambient air is at 21°C and has a dew point of 10°C. How much insulation with a conductivity of 0.18 W/(m K) is needed to prevent condensation on the exterior of the insulation if h = 2.4 W/(m2 K) on the outside?
GIVEN
FIND
Thickness of insulation (t) required to prevent condensation
ASSUMPTIONS
Steady state
Flow is fully developed
Pipe surface temperature can be considered uniform and constant
Radiation heat transfer to the insulation is negligible or included in ch ? Pipe is 1% carbon steel
SKETCH
PROPERTIES AND CONSTANTS
for dry air at –7°C by extrapolation
the thermal conductivity of 1% carbon steel (ks) = 52 W/(m K)
An object of mass m is hanging by a string from the roof of an elevator. The elevator is moving up at a constant speed. What is the tension in the string?
A. greater than mg B. less than mg C. equal to mg D. depends on the speed of the elevator
In which of the following energy level transitions for a hydrogen atom is a photon emitted?
a. n =1 to n = 2 b. n =3 to n = 2 c. n =2 to n = 1 d. n =1 to n = 4 e. n =4 to n = 3