When a wool blanket is used to keep warm, what is the primary insulating material?
a. wool
b. air
c. the trim around the edge of the blanket
d. a thin layer of aluminum foil (usually not apparent) inside the blanket
b
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From a fracture mechanics viewpoint, the reason freshly drawn glass fibers are stronger than window glass is that window glass has _________ that decrease its strength.
Fill in the blank(s) with the appropriate word(s).
Springs: A 3.0-kg brick rests on a perfectly smooth ramp inclined at 34° above the horizontal. The brick is kept from sliding down the plane by an ideal spring that is aligned with the surface and attached to a wall above the brick. The spring has a spring constant (force constant) of 120 N/m. By how much does the spring stretch with the brick attached?
A. 360 cm B. 240 cm C. 14 cm D. 24 cm E. 36 cm
The total mass of all the asteroids in the asteroid belt combined is
A) less than that of any terrestrial planet. B) about the same as that of Earth. C) about twice that of Earth. D) about the same as that of Jupiter. E) more than that of all the planets combined.
The free-stream flow outside a boundary layer is:
(A) Either laminar or turbulent, depending on the Reynolds number (B) A smooth flow free of disturbances (C) An irrotational flow (D) Neither laminar nor turbulent