The luminosity of a Seyfert galaxy varies with a regular period of months or years
a. True
b. False
Indicate whether the statement is true or false
False
You might also like to view...
Rub each of two inflated toy balloons with wool or fur. Will they attract each other or repel each other? Explain why
Two hockey pucks are initially at rest on a horizontal plane of frictionless ice. Puck A has twice the mass of puck B. Suppose we apply the same constant force on each puck until each puck has crossed a finish line 1 m away from its starting point. How do the puck’s kinetic energies compare when each crosses the finish line?
A. KA = 4KB B. KA = 2KB C. KA = KB D. KB = 2KA E. KB = 4KA F. Some other relationship (specify)
Which of the following is true of wavelengths of signals sent into space?
A) Wavelengths longer than 100 cm are absorbed in Earth's atmosphere. B) The interval between the 21-cm spectral line of neutral hydrogen and the 18-cm line of OH has very high background interference. C) Wavelengths longer than 100 cm get lost in the background noise of the Milky Way Galaxy. D) The interval between the 21-cm spectral line of neutral hydrogen and the 18-cm line of OH is narrow and can be monitored easily.
Two tanks of gas, one of hydrogen, H2, and one of helium, He, contain equal masses of gas. The gram-molecular mass of He is twice that of H2. Both tanks of gas are at the same temperature, 293 K. Which statement(s) below is(are) correct when we ignore vibrational motion?
A. The total internal energy of the hydrogen is the same as that of the helium. B. The total internal energy of the hydrogen is 167 times that of the helium. C. The total internal energy of the helium is 1.67 times that of the hydrogen. D. The total internal energy of the hydrogen is 3.33 times that of the helium. E. The total internal energy of the helium is 3.33 times that of the hydrogen.