When a star has stopped contracting and settled down, where is it in the H-R diagram?
A. below the main sequence in the lower left
B. in the upper right as a red giant
C. on the main sequence
D. in the instability strip
E. It is not on the H-R diagram at that time.
Answer: C
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When counting particle-in-a-box quantum states in three dimensions, why do we divide the “volume” of only one eighth of a full spherical shell by the “volume” per quantum state? Why not the full shell’s volume?
A. Molecules in a gas can only have positive momentum components. B. A single quantum energy state embraces both positive and negative values for each momentum component. C. A particle’s momentum magnitude must be positive. D. The factor of 2 in the expression h/2L already counts both possible momentum signs. E. We really do include the full shell: the diagram only shows 1/8 of the shell to make it easier to draw. F. Some other reason (specify).
In modern Miller—Urey experiments it is assumed that carbon and nitrogen in the early atmosphere were present as
A) methane (CH4 ) and ammonia (NH3) B) carbon dioxide (CO2 ) and nitrogen (N2) C) carbonates (CO3-) and nitrates (NO3-) D) carbon and nitrogen atoms
A meteor having a mass of 1000 kg moves through outer space, far from all planets and stars and far from all gravitational influences, at a speed of 20 km/s (20,000 m/s). How much work is done on the meteor during a time interval of one second?
A) 20 × 106 J B) 20 J C) 1000 J D) 20 000 J E) None of the above.
In an adiabatic compression, 200 J of work is done on a gas. What is the change in internal (thermal) energy of the gas during this compression?
A) 0 J B) 100 J C) 200 J D) -200 J