Tham khảo tài liệu 'anh ngữ sơ cấp - học tiếng anh bằng hình ành (phần 2) part 18', tài liệu phổ thông, tiếng anh phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | There is a good story about die use the great Italian scientist Galileo once made of his knowledge ci the pulse rate. Galileo lived three hundred years ago before men had watches for measuring time. In the sixteenth century there were very few clocks in the world and no watches. One day when Galileo was a young man of eight- ĩíTĩĩlìlTÌTRì church of the city of Pisa where he Jived. Watching the modem of a light hanging down on a long chain from the roof high above his head he saw that as the light moved forward and back on its chain it seemed to take die same time between turns however far it went 00 03 at one lima In the past forwards Io the front. chalos support erade of mefol rings going through one another. however fan when H went only a short distance and when it went a longer distance. bowevon In whatever way. 377 To see if he was right about the motion OÍ the light Galileo put his fingers on his wrist He timed the motion of the light as it went forward and back on its chain measuring it by his pulse rate. He was right He had the proof. He could prove that the time was the same however short or long the journey of the light through the air was. Galileo had made a great discovery about the motion of a pendulum. Among other things this discovery made possible a better instrument for measuring time the pendulum clock. pro oft that which makes clear that something Is so. timed meoswed tha time taken by. prove give proof. pendutanu hanging weight free to move from side Io side. will prove provofs will time time s proved timed 378 Measuring how fast somathing is moving gives US the rate of motion. This plane has gone 300 miles in half an hour. Iterate was 600 This man has walked two miles in half an hour. He was walking at a rate of four miles an hour. Now he is standing. He is -not moving. This man is working slowly. His pay will be small if he is paid by the amount of work he does in a day. This other man is working quickly. His pay will be high if he is .
