Question

रेलगाड़ीa रेलगाड़ी b को 30सैकण्ड में पार कर लेती है , यदि रेलगाड़ी Aकि चाल 72km/h है यदि रेलगाड़ी b की लम्बाई a के 140प्रतिशत हो तो दोनों रेलगाड़ीयो की लम्बाईयो का अन्तर ज्ञात कीजिए।​

Answer 1

Answer :-

$\sf{The\: difference\: between\: Lengths\:of\:trains\:is\:100\:m}$

Solution :-

$\boxed{\sf{GIVEN}}$

• Train A can overtake Train B in 30 sec .

• Speed of train A is 72 km/hr .

• Length of Train B = 140% of Train A .

$\boxed{\sf{To\: Find}}$

• Difference between the length of Train A and Train B .

____________________

→ Speed of train A = 72 km/hr.

So speed of train A in m / sec will be :-

→ Speed in m/sec = $\dfrac{72 \times 1000}{60\times 60}$

(Because 1km = 1000 m & 1 hour = 3600 seconds)

→ $\dfrac{72 \times 10}{6\times 6}$

→ $\dfrac{12 \times 10}{6}$

→ $\dfrac{12 \times 5}{3}$

→ $\sf{4\times 5}$

→ So the speed of train A =20 m/sec

Now train A can overtake train B in 30 sec .

And the trains are moving in same direction also .

→ So speed of train A = length of train B+Length of Train A/Time taken to overcome.

Let's assume that the length of train A = X and train B = y .

→ 20 m = $\sf{ \frac{x+y}{30}}$

→ 600 m = x+y .........eq 1st

→ y = 600 - x

So length of train B is 600 - x.

→ Now it's given that length of train A is equals to 1 40% of A

→ Length of train B = $\sf{ \frac{140 \times A}{100}}$

→ 600 - x = $\sf{ \frac{140 \times x}{100}}$

→ (600×100)-100x = 140x

→ 60000 = 140x + 100x

→ 60000 = 240x

→ 6000 = 24x

→ x = 250 m

So the length of train A is 250 m .

→ Putting the value of x in eq 1st

→ 600 = 250 + y

→ y = 350 m

So the length of train b is 350 metre .

→ Difference = 350 - 250

→ 100 m .