Problem: The hertz (symbol: Hz) is the derived unit of frequency in the International System of Units (SI) and is defined as one cycle per second. It is named for Heinrich Rudolf Hertz, the first person to provide conclusive proof of the existence of electromagnetic waves. Hertz are commonly expressed in multiples: kilohertz (10 Hz, kHz), megahertz (10 Hz, MHz), gigahertz (10 Hz, GHz), and terahertz (10 Hz, THz).

Some of the unit's most common uses are in the description of sine waves and musical tones, particularly those used in radio- and audio-related applications. It is also used to describe the speeds at which computers and other electronics are driven.

The hertz is equivalent to cycles per second, i.e., "1/second" or formula_1. The International Committee for Weights and Measures defined the second as "the duration of 9192631770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom" and then adds the obvious conclusion: "It follows that the hyperfine splitting in the ground state of the caesium 133 atom is exactly 9192631770 hertz, (hfs Cs) = 9192631770 Hz."

In English, "hertz" is also used as the plural form. As an SI unit, Hz can be prefixed; commonly used multiples are kHz (kilohertz, 10Hz), MHz (megahertz, 10Hz), GHz (gigahertz, 10Hz) and THz (terahertz, 10Hz). One hertz simply means "one cycle per second" (typically that which is being counted is a complete cycle); 100Hz means "one hundred cycles per second", and so on. The unit may be applied to any periodic eventfor example, a clock might be said to tick at 1Hz, or a human heart might be said to beat at 1.2Hz. The occurrence rate of aperiodic or stochastic events is expressed in reciprocal second or inverse second (1/s or s) in general or, in the specific case of radioactive decay, in becquerels. Whereas 1Hz is 1 cycle per second, 1 Bq is 1 aperiodic radionuclide event per second.
1. What is a hertz?
2. What does it measure?
3. Anything else?
4. Like what?
5. How did it get its name?
6. Who is he?
7. Is it used only in English-speaking countries?
8. How do you know that?
9. What time span is used in defining the measurement?
10. How long is a second?
11. Who decided that?
Answer: 1. the derived unit of frequency
2. sine waves
3. yes
4. also the speeds at which computers are driven.
5. It is named for Heinrich Rudolf Hertz
6. the first person to provide conclusive proof of the existence of electromagnetic waves
7. no
8. it is in the International System of Units (SI)
9. a second
10. "the duration of 9192631770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom"
11. The International Committee for Weights and Measures

Problem: According to Pete Singer, a researcher who wrote a number of books on the military, active involvement of robots in battles could worsen warfare by making machines do all the dirty work for humans. He says that humanity is currently at point of breakthrough in war, like the discovery of the atomic bomb. "What does it mean to go to war with US soldiers whose hardware is made in China and whose software is made in India?" The research predicts that by 2015 American soldiers will be half robots, half humans. It is worth mentioning that attack drones and bomb-handling robots are just some of the devices that armies use in battles. Besides having no mercy in battle, robots, in contrast to humans, also cut off living soldiers from horrors. "The United States is ahead in military robots, but in technology there is no such thing as a permanent advantage," Mr. Singer said, adding that currently Russia, China, Pakistan and Iran are working on the development of military robots as well. The researcher mentioned that robotics is something terrorists can take advantage of as well. "You don't have to make robots believe they are going to get 7 million dollars when they die to get them to blow themselves up," he said. In addition, Mr. Singer mentioned that military robots feature cameras that record everything a machine sees, providing digital video that is uploaded on You Tubein graphic clips, which soldiers call "war porn". "It turns war into entertainment, sometimes set to music. The ability to watch more but experience less," he said. David Hansco, who is a robotics designer, creates robots that have more features of a human. For example, his robots feature synthetic flesh faces and have the ability to read human facial expressions and copy them. The engineer states that the main idea is to create robots that can show empathy .
1. who wrote books?
2. books on what?
3. Where does Hardware come from?
4. What do the robots feature?
5. for what?
6. what are the videos called?
7. by who?
8. who else is mentioned?
9. which designer is mentioned?
10. what does he design?
11. what is made in india?
Answer:
1. Pete Singer
2. military
3. China
4. cameras
5. record everything a machine sees
6. war porn
7. soldiers
8. unknown
9. David Hansco
10. robotics
11. software