Question
1800 metres long train crosses a man who is moving in
the same direction with a certain speed, in 90 seconds. If the same train can cross a tree in 18 seconds with the same speed, then find the speed of the man.Solution
Speed of train = 1800/18 = 100 m/sec Let the speed of the man be βsβ m/sec Relative speed of the train = (100 β s) m/sec According to the question, (100 β s) = 1800/90 Or, s = 100 β 20 = 80 Therefore, speed of the man = 80 m/sec
The refractive index of water and turpentine oil are 1.33 and 1.47, respectively. A ray of light travels from
turpentine oil to water. The re...
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