The energy source at the center of our galaxy
a. is not visible at optical wavelengths.
b. produces X-rays.
c. must be less than 10 AU in diameter.
d. all of the above
e. none of the above.
D
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What kind of planets are most easily detected using the Doppler method?
A) high mass planets far from their host star B) low mass planets far from their host star C) low mass planets close to their host star D) high mass planets close to their host star E) planets that have been ejected from their systems
Two spacecraft in outer space attract each other with a force of 20 N. What would the attractive force be if they were one-half as far apart?
A. 5 N B. 10 N C. 40 N D. 80 N
Photon A has an energy of 3.3 × 10^–19 J. Photon B has 4 times the frequency of Photon A. What is the energy of Photon B?
a. 8.3E–20 J b. 1.7E–19 J c. 1.3E–18 J d. 6.6E–19 J e. 5.3E–18 J
The velocity of a particle (m = 10 mg, q = ?4.0 ?C) at t = 0 is 20 m/s in the positive x direction. If the particle moves in a uniform electric field of 20 N/C in the positive x direction, what is the particle's speed at t = 5.0 s?
a. 60 m/s b. 20 m/s c. 45 m/s d. 40 m/s e. 70 m/s