The figure shows two point sources of light, A and B. B emits light waves that are +? radians out of phase with the waves from A. A is 3? from P. B is 5? from P. (? is the wavelength.) The phase difference between waves arriving at P from A and B is
A. 0 rad.
B. ? rad.
C. 2? rad.
D. 3? rad.
E. 4? rad.
Answer: D
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A gas eventually will escape from a planet's atmosphere if the average velocity of the atoms exceeds 1/6 times the escape velocity of the planet. If the average velocity of water vapor in Venus's atmosphere is 0.9 km/s, would it eventually escape into outer space? Note that Venus's mass is 5 × 1024 kg, and its radius is 6,050 km.
a. Water vapor would escape because 1/6 times the escape velocity is 0.51 km/s. b. Water vapor would not escape because 1/6 times the escape velocity is 1.7 km/s. c. Water vapor would escape because 1/6 times the escape velocity is 0.42 km/s. d. Water vapor would not escape because 1/6 times the escape velocity is 2.6 km/s. e. Water vapor would escape because 1/6 times the escape velocity is 1.3 km/s.
A sample of argon gas (molar mass 40 g) is at four times the absolute temperature of a sample of hydrogen gas (molar mass 2 g). The ratio of the rms speed of the argon molecules to that of the hydrogen is:
A. 1 B. 5 C. 1/5 D. ?5 E. 1/ ?5
If the scalar (dot) product of two vectors is negative, it means that
a. there was a calculator error. b. the angle between the vectors is less than 90 degrees. c. the angle between the vectors is 90 degrees. d. the angle between the vectors is greater than 270 degrees. e. the angle between the vectors is between 90 and 180 degrees.
An 8.00 kg object has a moment of inertia of 1.50 kg 
If a torque of 2.00 N•m is applied to the object, the angular acceleration is
A. 0.750 
B. 1.00
C. 1.33
D. 2.01
E. 2.67