Unseen objects in our galaxy have been found by the bending effect they have on more distant stars' light passing near them. These small objects that don't emit light are calculated to have masses of about 10× the mass of the Sun. Which is the best choice for these objects?
a. black hole
b. neutron star
c. white dwarf
d. main-sequence stars
a
RATIONALE: Hint: Rank the objects by size, then add the mass.
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An eclipsing binary will
a. be more luminous than a visual binary. b. also be observed as a spectroscopic binary. c. give off most of its light in the infrared. d. show a constant Doppler shift in its spectral lines. e. show two stars with variable proper motion.
If the mass of a cart is quickly loaded to have twice the mass while a propelling force remains constant, the cart's acceleration
A) quadruples. B) doubles. C) stays the same. D) halves. E) none of these
A charge of 8.0 pC is distributed uniformly on a spherical surface (radius = 2.0 cm), and a second charge of -3.0 pC is distributed uniformly on a concentric spherical surface (radius = 4.0 cm). Determine the magnitude of the electric field 5.0 cm from the center of the two surfaces
a. 14 N/C b. 11 N/C c. 22 N/C d. 18 N/C e. 40 N/C
In this video, angular momentum is only approximately conserved. This is because
Choose one: A. there are small external forces acting—friction and air resistance, for example. B. no quantities are ever really conserved. C. the person on the platform is exerting a force when she pulls her arms in and pushes them out. D. the measurement of angular momentum depends on your reference frame.