This is the correct answer and is much more consistent than any of the other options, resulting in much greater precision when tracking time. One second is defined to be 9 192 631 770 vibrations of a Cesium atom.
Which of the following would serve as the best time standard?
a. the buzzing of a mosquito
b. the rotation of Earth upon its axis
c. the vibration of a CS-133 atom
. a grandfather clock
Suppose that the three fundamental standards of the metric system were length, density, and time rather than length, mass, and time. The standard of density in this system is to be defined as that of water. Which of the following are among the considerations about water that you would need to address to make sure that the standard of density is as accurate as possible?
(i) that the amount of water is at some defined value
(ii) that the pressure of the water is at some defined value
(iii) that the temperature of the water is at some defined value
(iv) that the water is pure