SOLUTION: A train overtakes 2 persons who are walking in the same direction in which the train is moving. the first person is moving with a speed of 2km/h and the second person is moving wit

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Question 882048: A train overtakes 2 persons who are walking in the same direction in which the train is moving. the first person is moving with a speed of 2km/h and the second person is moving with a speed of 4km/h. The train passes them then completely in 9 seconds and 10 seconds respectively. Find the length of the train and speed of the train .
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
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train overtakes 2 persons who are walking in the same direction in which the train is moving.
the first person is moving with a speed of 2km/h
and the second person is moving with a speed of 4km/h.
The train passes them then completely in 9 seconds and 10 seconds respectively.
Find the length of the train and speed of the train .
:
Let L = the length of the train (in meters)
Let s = the speed of the train (in meters/sec}
:
Change km/h to m/sec
2 Km/h: %282%2A1000%29%2F3600 = .556 m/sec
3 Km/h: %284%2A1000%29%2F3600 = 1.111 m/sec
:
Two distance equations; dist = speed * time
L = 9(s-.556)
L = 10(s-1.111)
L = L, therefore
10(s-1.111) = 9(s-.556)
10s - 11.11 = 9s - 5
10s - 9s = 11.11 - 5
s = 6.11 m/sec is the speed of the train;
Find L
L = 10(6.11-1.11)
L = 10*5
L = 50 meters is the length of train
Speed in km/h
%286.11%2A3600%29%2F1000 = 22 km/hr is the speed of the train