Question

1. A train running at a certain speed crosses a stationary engine in 20 seconds. To find
out the speed of the train, which of the following information is necessary ?
(a) Only the length of the train
(b) Only the length of the engine
(c) Either the length of the train or the length of the engine
(d) Both the length of the train and the length of the engine​

Answer 1

Answer:

Hey dear,

◆ Answer -

v = 40 m/s

◆ Explaination-

# Given-

Length of train l = 100 m

Time to pass t = 5 s

# Solution-

For a train to pass another train, it runs its own length and lenth of another train. i.e. distance = 2l

Velocity is calculated by-

Velocity = Distance / Time

v = 2l / t

v = 2×100 / 5

v = 40 m/s

Therefore, train is traveling at a speed of 40 m/s.

Hope this helps you..

Answer 2

Answer:

To find the speed of train, both the length of train as well as length of stationary engine will be required.

Therefore the option (d) is correct.

Step-by-step explanation:

Consider the length of the train is $L_{1}$

The length of the engine is $L_{2}$

Total distance travelled by the train to cross the engine $=L_{1}+L_{2}$

The time taken by train $=20sec$

Then speed of train = (Total distance)/(Time taken )

                                 $= \frac{L_{1}+L_{2}}{20}$

Therefore both L₁ and L₂ are required.