Two trains, A and B are travelling opposite directions. A is 100 m London and crossed a pole in 5 sec. A took 2.5 sec to cross the train B . If length of train B is 150 m. Find the speed of Train B
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Two trains, A and B are travelling opposite directions. A is 100 m London and crossed a pole in 5 sec. A took 2.5 sec to cross the train B . If length of train B is 150 m. Find the speed of Train B
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Verified answer
To find :
The speed of train B
Given :
time taken to cross a pole (A) = 5 s
time taken to cross B (A ) = 2.5 s
length of train A = 100 m
length of train B = 150 m
Formula to be used
Solution :
Train A crossed a pole in 5 sec . this means it crossed 100 m in 5 s hence, speed of train A :
[tex] \longrightarrow \bold{speed \: = \frac{distance}{time} } \\ \longrightarrow \bold{speed = 100 \div 5} \\ \longrightarrow \fcolorbox{blue}{yellow}{ \red{speed = 20 \: mps}}[/tex]
Let's assume that speed of Train B is x
hence, relative speed = 20m/s +x
total length of trains = 100+150 m
= 250 m
[tex] \boxed{ \bold {\green{time \: = distance \: \div speed }}}[/tex]
hence, 2.5 sec = 250/20+x
[tex] \longrightarrow \bold{2.5 = \frac{250}{20 + x} } \\ \longrightarrow \bold{ \frac{20 + x}{250} = \frac{1}{2.5} } \\ \longrightarrow \bold{20 + x = 100} \\ \longrightarrow \: \bold{x = 100 - 20} \\ \longrightarrow \: \bold{x = 80 \: mps }[/tex]
hence, speed of train B is 80 m/s
To find :
The speed of train B
Given :
time taken to cross a pole (A) = 5 s
time taken to cross B (A ) = 2.5 s
length of train A = 100 m
length of train B = 150 m
Formula to be used
relative speed (same direction) = greater speed-lesser speed
relative speed (opposite direction) = greater speed + lesser speed
Solution :
Train A crossed a pole in 5 sec . this means it crossed 100 m in 5 s hence, speed of train A :
Let's assume that speed of Train B is x
hence, relative speed = 20m/s +x
total length of trains = 100+150 m
= 250 m
hence, 2.5 sec = 250/20+x
hence, speed of train B is 80 m/s
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