SOLUTION: A train passes two bridges of lengths 800 m and 400 m in 100 seconds and 60 seconds respectively The length of the train is?

Question 413916: A train passes two bridges of lengths 800 m and 400 m in 100 seconds and 60 seconds respectively The length of the train is?
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
A train passes two bridges of lengths 800 m and 400 m in 100 seconds and 60 seconds respectively The length of the train is?
:
Let s = the speed of the train in meter/sec
Let L = length of the train
:
Write a distance equation for each bridge; dist = speed * time
Train + bridge = total dist
L + 800 = 100s
L + 400 = 60s
:
Multiply the 1st equation by 6, multiply the 2nd equation by 10
10L + 4000 = 600s
6L + 4800 = 600s
---------------------subtraction eliminates s, find L
4L - 800 = 0
4L = 800
L =
L = 200 meters is the length of the train
:
:
Check the solution by finding the speed, using the 1st equation
200 + 800 = 100s
1000 = 100s
s = 10 meter/sec is the speed
:
Check solution in the 2nd equation
200 + 400 = 60(10); confirms our solution of L = 200
RELATED QUESTIONS
A train is 90 meters long and enters a 310 meter long tunnel at a speed of 4 m/s . how... (answered by mananth)

The total length of train A and train B together is 777 m. Train B can cross an electric... (answered by TimothyLamb)

A train running at a uniform speed passes a bridge 275m long in 15 seconds and another... (answered by ankor@dixie-net.com)

Hello! Can someone help please? My question is: Two trains travel in the same... (answered by longjonsilver,psbhowmick)

A train overtakes 2 persons who are walking in the same direction in which the train is... (answered by ankor@dixie-net.com)

A train running at the speed of 90 km/hr crosses a platform of length 160 m in 10... (answered by stanbon)

Two trains of equal length are running on parallel lines in the same direction at 46... (answered by josmiceli)

A train B speeding with 1290 km/ h crosses another train C running in the same direction, (answered by mananth)

A train goes past you in 10 seconds and goes past a 100 meter long bridge in 30 seconds.... (answered by ikleyn)