Emission nebulae like M42 occur only near stars that emit large amounts of
A) infrared heat.
B) X-rays and gamma rays.
C) microwaves.
D) ultraviolet radiation.
E) visible light.
D
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What is the mean free path of molecules in an ideal gas in which the mean collision time is 3.00 × 10-10 s, the temperature is 300 K, and the mass of the molecules is 6.00 × 10-25 kg?
A) 7.22 × 10-8 m B) 4.32 × 10-8 m C) 9.19 × 10-8 m D) 1.39 × 10-8 m E) 6.71 × 10-8 m
Mercury's surface most resembles that of which other body?
A) Earth B) Moon C) Venus D) Mars E) Io
An object of mass m is hanging by a string from the roof of an elevator. The elevator is increasing its upward speed. What is the tension in the string?
A. greater than mg B. less than mg C. equal to mg D. depends on the speed of the elevator
A nonprismatic cantilever beam of one material is subjected to load P at its free end. Moment of inertia I2 5 2I1. The ratio r of the deflection ?B to the deflection ?1 at the free end of a prismatic cantilever with moment of inertia I1 carrying the same load is approximately:
(A) 0.25
(B) 0.40
(C) 0.56
(D) 0.78
