Aptitude - Problems on Trains - Discussion

Discussion Forum : Problems on Trains - General Questions (Q.No. 1)
1.
A train running at the speed of 60 km/hr crosses a pole in 9 seconds. What is the length of the train?
120 metres
180 metres
324 metres
150 metres
Answer: Option
Explanation:

Speed = 60 x 5 m/sec = 50 m/sec.
18 3

Length of the train = (Speed x Time).

Length of the train = 50 x 9 m = 150 m.
3

Discussion:
636 comments Page 6 of 64.

Comet Assistant said:   8 months ago
@All.

Clear and well-explained!

The key is converting km/hr to m/s using the multiplication factor of 5/18.
This comes from the conversion: 1 km/hr = (1000 m)/(3600 s) = 5/18 m/s.
Once we have the speed in m/s, we can easily multiply it by the time to get the distance.
(39)

Sparsh said:   5 years ago
I thought the timelapse is started when the front portion of the train just comes in contact with the bridge. If that were the case then the total length covered in 30 seconds is the length of the train twice plus the length of the bridge. So, the answer comes to be 115m.

Kenshika venistran said:   4 years ago
We know that 1 kilometre = 1000 meters and 1 hour = 3600 seconds.
Now, 1 km/h can also be written as 1000/3600: 1 (kilometre/hour) = 1000/3600 (meters/seconds).
So, this is the formula which is used to convert km/h to m/s.
On simplifying 1000/3600 further, we get 5/18.
(73)

Suganthan.m said:   2 decades ago
From the question we can predict speed= distance/hour
((by speed=60 km/hr)note the km/hr)
As to calculate for 9 sec I am converting the whole things to seconds
(i.e.)speed=60000/3600=16.666666(remember this is for one second)

therefore for 9 seconds
16.666666*9= 150

Roko Meena said:   1 decade ago
By using unit logic we can solve this question easily in question (given unit are km, m, sec).

Length of train in meter.

So, 60 km/hr.

= 60*1000 m/1*3600 sec.

1 km = 1000 m and 1 hour = 3600 sec.

= 1000 m*9 sec/3600 sec.

Sec unit cancel so I find (meter) 150 m.

BIJAY said:   5 years ago
@All.

We know that;
Velocity = Distance/Time.
so we can write,
Distance = Velocity*Time.
= (16.66)*(9) meters [=> 60km/hr convert into meters = 60*5/18. = 16.66 meter/sec.].
= 150 meters. [ANS].

Kaustubh Kishor Salunkhe said:   2 years ago
@All Everyone,

For the people who asking how 5/18 came?

It is used to convert KMPH to MPS
Let me explain how and when to use it. The hint is in the Answers we can see 60 km/hr and answers in Meters.
If it's Vise Versa we will use 18/5 to get the answer in Kmph.
(6)

Deepak said:   1 year ago
@All.

Here's my explanation:

1. You have to convert speed km/h into m/s.
And the formula to convert speed km/h into m/s is 60 x 5/18 (Note : 5/18 is a constant).
Speed = 16.67 m/s.

2. Distance = speed X time.
16.67 x 9 = 150m is the length of the train.
(18)

Satyapal khetlan said:   1 decade ago
Given: Train velocity = 60 km/hr;

It's mean that at 1 hr, traveled distance by train, is 60 km;

1 sec. travel distance = 60,000/(3600) m (1 hr = 3600 sec. & 1 km = 1000 m).

So, 9 sec " " = (100/6)*9 m.

= 150 m.

So, 150 m, should be correct answer;

Sundar said:   2 decades ago
@Contactjerin

Feet to Meter conversion: 1 feet = 0.3048 meter
Meter to Feet conversion: 1 meter = 3.28083 feet

This is what I mentioned already in this discussion.

You can easily find the answer for your question that is:

3.28083 feet = 1 meter.


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