Dark matter is ___
a. a cloud of black holes and brown dwarfs in the galactic halo
b. extremely cold, supermassive molecular clouds in the disk
c. an unknown type of mass that does not emit or absorb photons
d. the substance of which black holes are made
e. a theory to explain galactic formation that has been proven wrong
c
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What is the relationship between color and wavelength for light?
a. Wavelength increases from blue light to red light. b. Wavelength decreases from blue light to red light. c. All colors of light have the same wavelength. d. Wavelength depends on intensity not color.
The stellar spectral sequence, in order of decreasing temperature, is
A) OBAFGKM. B) OFBAGKM. C) OBAGFKM. D) ABFGKMO. E) BAGFKMO.
To recharge a 12-V battery, a battery charger must move 3.6 × 10^5 C of charge from the negative to the positive terminal. What amount of work is done by the battery charger? How many kilowatt hours is this?
A 3.0-kg object moving in the positive x direction has a one-dimensional elastic collision with a 5.0-kg object initially at rest. After the collision the 5.0-kg object has a velocity of 6.0 m/s in the positive x direction. What was the initial speed of the 3.0 kg object?
a. 6.0 m/s b. 7.0 m/s c. 4.5 m/s d. 8.0 m/s e. 5.5 m/s