Question

A train running at 36 km/h crosses a mark on
the platform in 8 sec and takes 20 sec to
cross the platform. What is the length of the
platform?
1. 120 m
2. 280 m
3. 40 m
4. 160 m​

Answer 1

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Speed of the Train = 36 km/hr.

= 36 × 5/18  [Changing into m/s]

= 2 × 5

= 10 m/s.

Given❇

Time taken to cross the Platform = 20 seconds.

Time taken to cross the platform = 08 seconds.

∵ Speed of the Train = Length of the Train/Time to cross the platform

∴ Length of the Train = Speed of the Train × Time to cross the platform.Speed of the Train = 36 km/hr.

= 36 × 5/18  [Changing into m/s]

= 2 × 5

= 10 m/s.

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Given❇

Time taken to cross the Platform = 20 seconds.

Time taken to cross theplatform = 10 seconds.

∵ Speed of the Train = Length of the Train/Time to cross the platform

∴ Length of the Train = Speed of the Train × Time to cross the

platform .

   = 10 × 10

   = 100 m.

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Now,

Sum of the Length of Platform and train = Speed of the Train × Time taken by the Train to cross the Platform.

= 10 × 20

= 200 m.

∵  Length of the Train + Length of the Platform = 200

∴  100 + Length of the Platform = 200

∴ Length of the Platform = 200 - 100

   = 100 m.

∴ Length of the Platform is

   = 10 × 08

   = 80 m.

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Now,

Sum of the Length of Platform and train = Speed of the Train × Time taken by the Train to cross the Platform.

= 10 × 20

= 200 m.

∵  Length of the Train + Length of the Platform = 200

∴  100 + Length of the Platform = 200

∴ Length of the Platform = 200 - 80

   = 120 m.

∴ Length of the Platform is 120 m.

Option a) 120 I'd correct.

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