Which statement about the behavior of Universe geometries is correct?
a. Closed and open universes expand forever
b. Closed universes expand and then contract.
c. Only flat universes expand forever.
d. Flat and open universes expand and then contract.
e. Only flat universes expand and then contract.
b
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Clusters of galaxies are distributed in space ____
a. homogenously b. isotropically c. in long, narrow filaments surrounding empty voids d. statically e. in bubbles surrounded by empty walls
Wave Characteristics: An electromagnetic wave travels in free space in the +y direction, as shown in the figure. If the electric field at the origin is along the +z direction, what is the direction of the magnetic field?
A. +z B. -z C. +y D. +x E. -x
A 3.0-kg cat runs to the left at 10 m/s and a 10-kg dog runs to the right at 4.0 m/s. The total kinetic energy is
A. 146 Joule. B. -35 Joule. C. -70 Joule. D. 230 Joule. E. 0.
The speed of a 10-kHz sound wave in seawater is approximately 1 500 m/s. What is its wavelength in sea water?
a. 5.0 cm b. 10 cm c. 15 cm d. 20 cm e. 29 cm