The first to be credited with the idea that light is quantized was
A) Max Planck.
B) Albert Einstein.
C) both Planck and Einstein at about the same time.
Answer: B
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A 5.0-m radius playground merry-go-round with a moment of inertia of 2000 kg • m2 is rotating freely with an angular speed of 1.0 rad/s
Two people, each having a mass of 60 kg, are standing right outside the edge of the merry-go-round and step on it with negligible speed. What is the angular speed of the merry-go-round right after the two people have stepped on? A) 0.20 rad/s B) 0.40 rad/s C) 0.60 rad/s D) 0.80 rad/s E) 0.67 rad/s
A parallel-plate capacitor has dimensions 4.3 cm × 4.6 cm. The plates are separated by a 1.0-mm thickness of paper (dielectric constant ? = 3.7). What is the charge that can be stored on this capacitor, when connected to a 1.2-V battery? (?0 = 8.85 × 10^?12 C2/N?m2)
a. 2.0 × 10^?12 C b. 3.9 × 10^?12 C c. 3.9 × 10^?11 C d. 7.8 × 10^?11 C e. 6.8 × 10^?11 C
The mass of a star is 8.0 × 10^30 kg, and the mass of a hydrogen atom is 1.67 × 10^?27 kg. If we assume that the star is mostly composed of hydrogen, approximately how many atoms are there in the star?
a. 1.3E+4 atoms b. 2.1E–58 atoms c. 4.8E+57 atoms d. 8.0E+30 atoms
Ellis and Randy are looking at a molecular absorption spectrum. The spectral lines appear to fall into two groups with a gap in the middle. Ellis says that this must be an absorption spectrum for transitions between the v = 0 and v = 1 vibrational states of a diatomic molecule. Randy says the gap in the middle must occur because a ?J = 0 transition is forbidden. Which one, if either, is correct,
and why? a. Ellis, because rotational levels are separated by greater energy differences than vibrational levels. b. Randy, because rotational levels are separated by greater energy differences than vibrational levels. c. Ellis, because the ?J = 0 transition is the most prominent spectral line in transitions between vibrational levels. d. Neither, because rotational levels are separated by greater energies that vibrational levels and ?J = 0 transitions are not forbidden. e. Both, because vibrational levels are separated by greater energy differences than rotational levels and ?J = 0 transitions are forbidden.