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A train 100 meters long moving at a speed of 50 km/h crosses a train 120 metres long coming from opposite direction in 6 seconds. What is the speed of second train in km/h?

 Jul 8, 2020
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Approach (closing speed) speed  is   50+x

 

in 6 seconds at this speed the trains must cover 100 m + 120 m = 220 m

   (it is like holding one completely still..... when the engines meet the moving train must move 100 m to get the 'caboose' to the nose of the non-moving train....then an ADDITIONAL 120 m to get that caboose the end of the non-moving train....do you see?)

 

220 m /1000 m/km   /   (6 sec / 3600 sec/hr)    = 50 +x    km/hr

x = 82 km/hr

 Jul 8, 2020

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