In quantitative aptitude, Train problems are the most frequently asked questions in form of Time and Speed questions. It involves the speed, time, and distance concept, including relativity theory also.
In this article, we will get to know how to deal with train problems.
Basic Concepts
So let first see the basic concept:
Distance: When an object simply moves from one place to another. We measure it in Km or m.
Time: It represents how much time an object needs to cover a particular distance. We measure it in hr or s.
Speed: It simply represents at what pace an object is moving. We measure it in km/hr or m/s.
These three things relate to each other and give us a formula which is:
Speed = Distance/Time
v=s/t
Types of Questions Normally Asked from Train Problem
Asking Questions where conversion is needed
- Converting Km/h to m/s =meter/ (minute * seconds) = 1000/(60*60) = 5/18 m/s
- Converting m/s to Km/h = (minute * seconds) / meter = (60*60)/ 1000 = 18/5 Km/h
Q. A train moves with a speed of 10 km/h. What distance it will cover in 20 s?
First, convert the speed in m/s = 10 *5 /18 = 50/18 m/s
Now find the distance = d = s * t
d = (50/18)* 20 = 55.5 m
Asking Direct Question where two parameters are given and required to find the third one by simply using the distance formula
- Use, Speed = Distance/time
Q. A train moves with a speed of 10 km/h. Find its distance after traveling for 2 hours?
Speed =10km/h
Distance= ?
Time = 2 hrs
10km/h = ?/2 hrs
distance = 10km/h *2 hrs
distance = 20km
Asking a question about a moving object relative to a stationary object such as a person, bridge, platform, and more
- If a stationary object is a poll, person or a tree and to know when a moving object would completely cross that stationary object= length of object/ speed
- If a stationary object is a bridge, platform and to know when a moving object would completely cross that stationary object= length of object + length of platform or bridge/ speed
Q. A train is 600 m long and moving with a speed of 200 m/s. What time does it cross 600 m long Platform?
Speed = 200 m/s
Distance = ( length of train + length of platform) / t
t = (600m + 600m )/200 m/s
t = 1200m/200 ms
=6 s
Asking Train Problem Questions based on Relativity Theory
- If two moving vehicle is moving in the same direction and to know at what time they cross each other
- Time = (length of first moving object + length of a second moving object)/ (Speed of the first train – Speed of the second train)
- If two moving vehicle are moving in opposite directions and to know at what time they cross each other
- Time = (length of first moving object + length of a second moving object)/ (Speed of the first train + Speed of the second train)
- If two moving vehicle is moving in the same direction and to know at what time they cross each other
Q. Train A 200 m long moves with a speed of 150 m/s and Train B 300 m long moves with a speed of 150 m/s. If both trains are opposite to each other, at what time they cross each other.
Distance = length of train A + length of train B = 200 + 300 = 500 m
Speed = speed of train A + speed of train B = 150 + 150 = 300 m/s
t = 500/300 = 5/3 s
