The photons from the microwave background have not interacted with matter since the universe was how old?
A) 4,000,000,000 years old
B) 4,000,000 years old
C) 400,000 years old
D) 4,000 years old
E) 4 seconds old
C
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Suppose that at a certain time a quanton has a well-defined position x = 0.15 nm. At that time, we perform an experiment to determine the quanton’s momentum, and find it has a value that corresponds to a de Broglie wavelength of 0.45 nm to a high degree of precision. What can we say about the quanton’s position after the experiment?
A. It is still 0.15 nm. B. It is now 0.45 nm. C. It is now within ±0.45 nm of 0.15 nm. D. It is now undefined but probably close to 0.15 nm. E. It is now completely undefined. F. Other (specify).
A 0.50-mF capacitor is connected to a 400 V battery. Find the charge on the capacitor
a. 2.0 × 10^-4 C c. 1.0 × 10^-4 C b. 0.020 C d. 1.2 × 10^-12 C
The horizontal speed of a projectile
a. is zero. b. stays constant. c. continuously increases. d. continuously decreases. e. sometimes decreases and sometimes increases.
An external heat source supplies heat to a system at a rate of 187 W as the system does work at a rate of 131 W. At what rate is the internal (thermal) energy of the system changing?
A) 320 W B) 56 W C) 190 W D) -56 W E) -320 W