Question

a train 420m long is running at a speed of 90km/hr .if it crosses a platform in 45sec find the length of platform​

Answer 1

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First of all we will convert the speed to m/s

To convert to m/s, multiply with 5/18

90 km/hr = 90 × 5/18 m/s

→ 25 m/s

Now given that it crosses the platform in 45 seconds. Let the length of platform be x

So, total distance travelled by train = Length of platform + Length of train

= x + 420 m

Time = 45 seconds

Speed = 25 m/s

we know that, speed = distance/time

So, substitute the values of speed, distance and time

→ 25 = (x + 420)/45

→ x + 420 = 45 × 25

(By cross multiplication)

→ x + 420 = 1125

→ x = 1125 - 420

→ x = 705 m

Hence, the length of the platform is 705 m

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Answer 2

Answer:

705

Step-by-step explanation:

let the lenght of platform be x

lenght of train= 420m

time= 45sec

speed=90km/hr

=90×5/18

=25m/s

a/q,

S×T=D

25×45=420+x

1125=420+x

1125-420=x

705=x

hence the length of platform is 705

.........666........