Question

A maglev train crosses a very tiny rose sapling in 5 seconds but it takes 45 seconds to cross a stationary sleeper chair of length 400 m. What was the speed of the train at which it passed through sapling and chair?
1. 10 m/s
2. 12 m/s
3. 13 m/s
4. 8 m/s

Answer 1

Correct Answer - Option 1 : 10 m/s

Calculation

Time taken by maglev train to cross rose sampling is 5 seconds

Let the length of a maglev train be L and speed be S.

As we know in case of negligible length object,

L_T = S × t

Where L_T is the length of the train

S is the speed of train

t is the time taken to cross

⇒ L = 5 × S      ----(I)     

And we also know,

When an object is of considerable length then,

Lt + length of Object = S × t

⇒L + 400 = 45S      ----(II)

Substituting the value of L from (I) in (II)

We get, S = 10 mps

∴ Speed of train is 10 m/s.

When a train crosses a non-moving object of considerable length, its length is also included hence formula derives:

L_T + length of the object = Speed × time

While when object has negligible length we conclude :

L_T = Speed × time