Question

Example 3. Two trains 120 m and 180 m long are running in opposite
direction on parallel rails. Their speeds are 40 km per hour and 35 km per hour.
Find the time taken to pass each other.
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Answer 1

Answer:

LET THE LENGTH OF FIRST TRAIN (L1) = 120 m

LENGTH OF 2ND TRAIN (L2) =. 80

SPEED OF FIRST TRAIN (S1)=42 km/h

SPEED OF 2ND TRAIN (S2)=30km/hr

Step-by-step explanation:

NOW FORMULA IS =

speed= distance/ time

so,

S1+S2=(L1+L2)/TIME

(42+30)km/he=200m/time..

now convert the speed from km/he to m/s by multiplying 5/18,..

72*5/18=200/time

20m/s=200m/s

TIME=20/20

TIME=10SECONDS..

so , the train will cross each other in 10 seconds.,

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ITZ BHUMIKA

Answer 2

Answer:

• 2.4 mins

Given:-

• Two trains 120 m and 180 m long are running in opposite direction on parallel rails.
• Their speeds are 40 km per hour and 35 km per hour.

To Find:-

• The time taken to pass each other.

Step-by-step explanation:

▪The train would pass themselves after meeting, the two trains would cross the lengths of each train first.

▪So both of the train have to cross

= ( 120 + 180 ) m

= 300 m

▪The speed of the 1st train

= 40 km/hr

= 40000 m/hr

▪The speed of the 2nd train

= 35 km/hr

= 35000 m/hr

▪Both train are running in opposite direction, so in 1 hr they will cross

= ( 40000 + 35000 ) m

= 75000 m

→ 75000 m is crossed in 3600 sec ( 1 hr = 3600 sec )

→ 300 m is crossed in,

$\implies \sf \: \dfrac{3600}{75000} \times 300$

$\implies \sf \: \dfrac{1080000}{7500}$

$\implies \sf \: 144 \: sec.$

$\implies \sf \: 2.4 \: \: min$