Question

a train 150 m long is running at a uniform speed of 90 km/hr . Find :- (i) the time taken by it to cross a man standing on the platform
(ii)the time taken by it to cross a platform 280m long.​

Answer 1

Given:

• A train 150 m long is running at a uniform speed of 90 km/hr .

To Find:

(i) The time taken by it to cross a man standing on the platform.

(ii) The time taken by it to cross a platform 280 m long.

Solution:

i.)

• Speed of train = 90 × 5/18
• Speed of train = 30 × 5/6
• Speed of train = 10 × 5/2
• Speed of train = 5 × 5
• Speed of train = 25 m/s

Distance to be covered by train = 150 m

We know that,

♦ Speed = Distance/Time

Time = Distance/Speed

Putting the values,

• Time taken = 150/25
• Time taken = 30/5
• Time taken = 6 s

Therefore,

Time taken by it to cross a man standing on the platform = 6 s.

ii.)

Let the time taken by a train be T s.

We know that,

♦ Speed = Distance/Time

According to the question,

• 25 = (150 + 280)/T
• 25 = 430/T
• 25T = 430
• T = 430/25
• T = 17.2 s

The time taken by it to cross a platform 280 m long = 17.2 s

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