Relate the Galaxy's spiral arms to the spiral-density wave theory
What will be an ideal response?
Spiral-density waves compress the gas and dust and lead to new star formation, making these regions of higher density bright and blue with new stars. The wave motion is slower than the rotation, and not tied to it, so it can keep going for billions of years.
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For a rod in tension, what material class provides the highest specific critical-stress intensity factor?
(a) Steels (b) Titanium alloys (c) Aluminum alloys (d) Uni-ply composites (GFRP, CFRP, and KFRP)
Suppose the Sun were suddenly to shrink in size but that its mass remained the same. According to the law of conservation of angular momentum, what would happen?
A) The Sun would rotate faster than it does now. B) The Sun's rate of rotation would slow. C) The Sun's angular size in our sky would stay the same. D) This could never happen, because it is impossible for an object to shrink in size without an outside torque.
A 5.0-liter gas tank holds 1.4 moles of helium (He) and 0.70 moles of oxygen (O2), at a temperature of 260 K. The atomic masses of helium and oxygen are 4.0 g/mol and 16.0 g/mol, respectively
Avogadro's number is 6.022 × 1023 molecules/mol and the Boltzmann constant is 1.38 × 10-23 J/K. The total random translational kinetic energy of the gas in the tank is closest to A) 7.6 kJ. B) 6.8 kJ. C) 8.3 kJ. D) 6.1 kJ. E) 9.1 kJ.
Which would have the lower average molecular kinetic energy?
(i) a sample of hydrogen gas, H2, at 0°C (ii) a sample of oxygen gas, O2, at 100° C
1.(i) 2.(ii) 3.They have the same average molecular kinetic energy. 4.It is impossible to tell.