The meter is presently defined as
a. one ten-millionth of the diameter of Earth.
b. the wavelength of a line in the spectrum of krypton-86.
c. the length of a platinum-iridium bar.
d. the distance light travels in a vacuum in a very short time.
d
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Are comets common? Explain why or why not
What will be an ideal response?
An inventor develops a stationary cycling device by which an individual, while pedaling, can convert all of the energy expended into heat for warming water. How much mechanical energy is required to increase the temperature of 200 g of water (enough for 1 cup of coffee) from 18°C to 94°C? (1 cal = 4.186 J, the specific heat of water is 4 186 J/kg/°C)
a. 6.4E+4 J b. 3.2E+4 J c. 1.6E+4 J d. 1.0E+3 J e. 1.5E+1 J
Consider an orbit where rc = 1 AU and b = 2 AU. What kind of orbit is this?
A. Circular B. Elliptical C. Parabolic D. Hyperbolic
Which of the following statements about halo stars is false?
A) Halo stars have random orbits about the Milky Way center. B) Halo stars are no longer being formed at the current epoch. C) All halo stars are less massive than our Sun. D) Halo stars are made entirely of hydrogen and helium with no heavy elements. E) Halo stars are some of the oldest known objects in the universe.