Question

two trains of length 100metre and 80metre respectively run on parallel lines of rails .when running in the same direction the faster train passed the slower one in 18sec, but when they are running in opposite directions with the same speed as earlier, they pass each other in 9sec .find the speed of each train. ​

Answer 1

The speed of the faster train is 15 m/s and the speed of the slower train is 5 m/s.

Step-by-step explanation:

Required formula:

Relative speed = [Total distance] / [Time]

The length of the faster train = 100 m

The length of the slower train = 80 m

∴ The total length of the train = 100 + 80 = 180 m

Let the speed of the faster train be “s1” m/s and the speed of the slower train be “s2” m/s.

When the two trains are running in the same direction:

Relative speed = s1 – s2

Time taken to pass each other = 18 sec

Therefore, we get the eq. as,

$\frac{180}{s1 - s2}$ = 18

⇒ s1 – s2 = 180 / 18

⇒ s1 – s2 = 10 …… (i)

When the two trains are running in the opposite direction:

Relative speed = s1 + s2

Time taken to pass each other = 9 sec

Therefore, we get the eq. as,

$\frac{180}{s1 + s2}$ = 9

⇒ s1 + s2 = $\frac{180}{9}$

⇒ s1 + s2 = 20 …… (ii)

Adding eq. (i) & (ii), we get

s1 – s2 = 10

s1 + s2 = 20

--------------------

 2 * s1 = 30

-----------------

s1 = $\frac{30}{2}$ = 15 m/s

substituting the value of s1 in eq. (ii), we get

15 + s2 = 20

⇒ s2 = 20 – 15

⇒ s2 = 5 m/s

Thus, the speed of the faster train and the slower train is 15 m/s and 5 m/s respectively.

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Answer 2

Answer:

15km, 5km

Step-by-step explanation:

good evening everyone hope it is helpful