The stars farther than 20 000 LY from the center of the Milky Way are traveling too fast to be bound to the galaxy by the observed mass of the galaxy. Which of the following are currently being investigated as possible explanations of this?
a. neutrino mass
b. WIMPs
c. Newtonian dynamics are not quite correct.
d. all of the above
d
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A light beam shines through a thin slit and illuminates a distant screen. The central bright fringe on the screen is 1.00 cm wide, as measured between the dark fringes that border it on either side
Which of the following actions would decrease the width of the central bright fringe? (There may be more than one correct choice.) A) increase the wavelength of the light B) decrease the wavelength of the light C) increase the width of the slit D) decrease the width of the slit E) put the apparatus all under water
Nearsighted people wear glasses with
lenses that are designed to a) make the image larger. b) improve the focus of the image. c) make the image smaller. d) make the image brighter.
A metal wire has a resistance of 31 ? under room temperature conditions of 15°C. When the wire is heated to 81°C the resistance increases by 0.65 ?. What is the temperature coefficient of resistivity of this metal?
a. 3.2E–4 × 10^?4 (°C)?1 b. 2.5E–3 × 10^?3 (°C)?1 c. 1.4E–2 × 10^?3 (°C)?1 d. 3.1E–3 × 10^?3 (°C)?1 e. 1.4E–4 × 10^?4 (°C)?1
Most of the energy during the collapse of the iron core of a supergiant star is released in the form of neutrinos—nearly massless subatomic particles that rarely interact with matter. So how is it they can blow away a stars outer shells?
A) Although they rarely interact with matter, the sheer number released during the collapse is enough to move most of the star's mass into surrounding space at incredibly high rates of speed. B) By creating a massive magnetic field that convulses in on itself, ripping away the stars outer shells C) When neutrinos exceed a certain speed, 22,300 km/s, they interact with matter quite effectively. D) By developing a temporary, but relatively strong positive charge