Why can't current theories describe what happened during the Planck era?
A) We do not yet have a theory that links quantum Wmechanics and general relativity.
B) We do not understand the properties of antimatter.
C) We do not know how much energy existed during that time.
D) It was a time period from which we cannot receive radiation.
E) The Planck era was the time before the Big Bang, and we cannot describe what happened before that instant.
A) We do not yet have a theory that links quantum Wmechanics and general relativity.
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The planet Jupiter is 7.78 × 1011 m from the sun. How long does it take for Jupiter to orbit once about the sun given that the distance from the earth to the sun is 1.50 × 1011 m?
A) 2.3 years B) 5.2 years C) 6.0 years D) 12 years E) 27 years
An ideal gas is allowed to expand adiabatically until its volume increases by 50%. By approximately what factor is the pressure reduced? (? = 5/3.)
a. 1.5 b. 2.0 c. 2.5 d. 3.0 e. 3.5
Two converging lenses, the first with focal length 10.0 cm and the second with focal length 20.0 cm, are separated by 40.0 cm. An object, 3.00 cm in height, is placed 30.0 cm in front of the first lens. Where is the image caused by the first lens?
A. 7.50 cm after the first lens B. 7.50 cm after the second lens C. 15.0 cm after the first lens D. 15.0 cm after the second lens E. 55.0 cm after the second lens
Dielectrics: A parallel-plate capacitor consists of a set of two parallel plates of area A separated by a distance d. This capacitor is connected to a battery that maintains a constant potential difference across the plates. A slab of a dielectric material is inserted in the region between the plates and completely fills it. What changes would you observe as the dielectric is inserted? (There could be more than one correct choice.)
A. Only the charge on the plates of the capacitor would change. B. Only the capacitance would change. C. Both the charge on the plates of the capacitor and its capacitance would change. D. The potential difference across the plates would increase. E. Nothing would change.