Which of the following is an example of convection?
A) different kinds of material separating by density, like oil and water
B) rocks sinking in water
C) warm air expanding and rising while cooler air contracts and falls
D) gas bubbling upward through a liquid
C
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Energy Levels: In a transition from one vibrational state to another, a molecule emits a photon of wavelength 5.56 µm. What is the energy difference between these two states? (c = 3.00 × 108 m/s, h = 6.626 × 10-34 J ? s, 1 eV = 1.60 × 10-19 J)
A. 0.223 eV B. 2.23 MeV C. 13.6 eV D. 13.6 MeV E. 0.223 MeV
The speed of sound in air is dependent upon the air temperature and other factors. The speed of sound increases from 334 m/s to 341 m/s between 8:00am and 11:00am. If a horn produces sound with wavelength 0.75 m at 8:00am, what would it produce at 11:00am?
A. 73 cm B. 77 cm C. Not enough info given to solve. D. 75 cm
Which of the following is not a method astronomers use to determine the physical conditions inside the Sun?
A) observing x-ray images of the solar interior using satellites B) building mathematical models that use the laws of physics C) detecting solar neutrinos generated in the Sun's core D) measuring Doppler shifts to observe solar vibrations
An automobile travels due north with a constant speed of 81 km/h. All forces considered, the unbalanced force acting on the auto is
a. zero. b. southward. c. northward. d. downward. e. upward.