Melanie says that when a diver enters an underwater cave of height y, the pressure on her is no greater than ?Wgy. Rosalind says that if the bottom of the cave is a distance Y below the water surface, the pressure on the soles of the diver's feet can reach ?WgY. Which one, if either, is correct? (The density of water is ?W.)
a. Melanie, because the roof of the cave absorbs the water pressure from above.
b. Melanie, because only the fluid directly above any volume of the fluid can contribute to the pressure on that volume.
c. Rosalind, because a fluid exerts equal pressure in all directions at a given depth.
d. Rosalind, because the pressure also depends on ?c, density of the material above the cave roof, so that p = ?cg(Y ? y) + ?Wgy.
e. Melanie, because the pressure equals p = ?WgH ? ?cg(H ? h).
c
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Suppose that the three fundamental standards of the metric system were length, density, and time rather than length, mass, and time. The standard of density in this system is to be defined as that of water. Which of the following are among the considerations about water that you would need to address to make sure that the standard of density is as accurate as possible?
(i) That the amount of water is at some defined value. (ii) That the pressure of the water is at some defined value. (iii) That the temperature of the water is at some defined value. (iv) That the water is pure.
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A) it always appears as only half lit from Earth. B) it never gets more than 28 degrees from the Sun's glare. C) its elliptical orbit causes it to change speed unpredictably. D) its barren surface reflects too little sunlight; it is almost invisible always. E) its very rugged surface does not allow radar to bounce back to Earth.
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A. 20 N/C B. 14 N/C C. 4.0 N/C D. 12 N/C E. 8.0 N/C
Light of wavelength 687 nm passes through a single slit that is 0.75 mm wide. At what distance from the slit should a screen be placed so that the second dark fringe in the diffraction pattern is to be 1.7 mm from the center of the pattern?
A) 1.9 m B) 1.5 m C) 0.93 m D) 1.1 m E) 0.39 m