Q9. Man who received the most altercations for a theory which later on became a revolutionary theory influenced in many areas of modern science and technology.
Q10. Fire truck is coming towards you
Explanation:
Q9. Christian  Doppler was born on 29th of November 1803 in Saltzburg. After studies in Linz and Vienna, he graduated in Mathematics. For many years, Doppler struggled to find work in academia, and for a time he worked as a bookkeeper at a factory. His academic career took him from Austria to Prague, where he became assistant at the University and later worked as professor in Prague. Back to Vienna, he was appointed as professor at the Polytechnic School and in 1850 as first director of the new Institute of Physics. While working at Vienna, his health broke down and moved Venice where he sought his eternal rest on March 17th, 1953.
During his lifetime, the man was quite controversial: a personality praised by some, but detested by others; and even as a scientist, he had a difficult time. He did publish papers on magnetism, electricity, optics and astronomy but, the discovery that allowed him to remain in history of science was the one he presented at Royal Bohemian Society of Science entitled "On the colored light of the double stars and certain other stars of the heavens" in 1842. He hypothesized that the pitch of the sound would change if the source was moving.
Doppler's ideas were initially received with a certain amount of skepticism so, in order to support his claims, he devised an experiment in 1845 with the help of colleague. He used two sets of trumpeters, one set stationary at a train station and  one set moving on an open train car. Both sets of musicians had perfect pitch and held the same note. As the train passed the station, it was obvious that the frequency of the two notes didn't match, even though the musicians were playing same note. This proved his hypothesis.
Demonstrating that the Doppler effect also held true for frequency of ligh proved more difficult and was never successfully achieved before Doppler's demise. The first experiment that revealed a Doppler shift in starlight was carried out at the beginning of twentieth century. Since then Doppler effect was proved invaluable for astronomical observations.
For the most of the academic world, he is known as physicist; but one can equally find him on the list of mathematicians and astronomers too. This is proof for the exceptional broad spectrum of application of his main discovery.
Q10. When there is increase in frequency of the sound from source, then the source is moving towards you. Hence the fire truck is coming towards you
