Study Material — 4 PYQs (2022–2022) · Concept Notes · Shortcuts
SSC GD Constable Trains is a frequently tested subtopic — 4 previous year questions from 2022–2022 papers are included below with concept notes, key rules and shortcut tricks.
4 questions from actual SSC GD Constable papers · all shown free · click option to reveal solution
Exam Q 12022Previous Year Pattern
Two trains start simultaneously from opposite ends of a 600 km track. Train X travels at 80 km/h and Train Y at 70 km/h. A bird starts flying from the front of Train X towards Train Y at 120 km/h. When the bird meets Train Y, it immediately turns back and flies towards Train X. This process continues until the trains meet. What is the total distance covered by the bird?
Exam Q 22022Previous Year Pattern
A train starts from station A and travels towards station B at 72 km/h. After 3 hours, another train starts from station B towards station A at 90 km/h. If the distance between A and B is 540 km, at what distance from station A will the two trains meet?
Exam Q 32022Previous Year Pattern
Two trains of lengths 120 m and 180 m are moving in the same direction on parallel tracks. The faster train (120 m) travels at 90 km/h and the slower train (180 m) at 54 km/h. How long will it take for the faster train to completely overtake the slower train?
Exam Q 42022Previous Year Pattern
A train crosses a platform of length 150 m in 18 seconds and crosses a pole in 12 seconds. What is the length of the train?
Concept Notes
Trains— Rules & Concept
Core ConceptRead this first — the foundation of the topic
Core Concept
Train problems involve calculating time taken by trains to cross objects like poles, platforms, bridges, or other trains. The key is understanding that trains have length, unlike point objects
Key Rules
When a train crosses a stationary object like a pole, it travels a distance equal to its own length. When crossing a platform or bridge, it travels its own length plus the length of the platform/bridge. For two trains, use relative speed concept.
Formula BlockMemorise — at least one formula appears in every paper
Time = Distance/Speed
Speed = Distance/Time
Relative Speed (same direction) = |S1 - S2|
Relative Speed (opposite direction) = S1 + S2
Speed conversion: km/hr to m/s multiply by 5/18, m/s to km/hr multiply by 18/5
Exam PatternsWhat examiners ask — read before attempting PYQs
SSC CGL typically asks 1-2 train problems per paper. Common question types include trains crossing poles, platforms, bridges, and other trains. Questions often involve unit conversions and relative motion.
ShortcutsUse these to save 30–60 seconds per question
- The 5/18 Rule: To convert km/hr to m/s, multiply by 5/18. To convert m/s to km/hr, multiply by 18/5. Remember: 72 km/hr = 20 m/s (this conversion appears frequently).
Worked ExampleSolve this step-by-step before moving on
1
Step 1
Distance covered = Length of train = 120m
2
Step 2
Time taken = 8 seconds
3
Step 3
Speed = Distance/Time = 120/8 = 15 m/s
4
Step 4
Convert to km/hr = 15 × 18/5 = 54 km/hr
Answer: 54 km/hr
Worked Example 2: Two trains of lengths 100m and 150m are running in opposite directions at speeds 40 km/hr and 50 km/hr respectively. In how much time will they cross each other?
Relative speed = 100/9 + 125/9 = 225/9 = 25 m/s (opposite direction, so add)
3
Step 3
Total distance = 100 + 150 = 250m
4
Step 4
Time = Distance/Speed = 250/25 = 10 seconds
Answer: 10 seconds
Advanced Shortcut - Platform Formula: Time to cross platform = (Train length + Platform length)/Speed. This direct formula saves calculation steps in exams.
Most Common Trap: Students forget to add platform/bridge length when train crosses them. They only consider train length, leading to wrong answers. Always read whether the train crosses a pole (only train length) or platform/bridge (train length + platform/bridge length).
Another frequent mistake is wrong unit conversion. Practice the 5/18 conversion thoroughly. Many students confuse when to multiply or divide.
Speed-Distance-Time Shortcut: If train crosses pole in time T1 and platform in time T2, then platform length = speed × (T2 - T1). This eliminates the need to calculate train length first.
Two trains are moving towards each other. Train A travels at 60 km/h and Train B travels at 40 km/h. If they are 200 km apart, how long will it take for them to meet?
Practice 2easy
A train 150 metres long passes a stationary pole in 5 seconds. What is the speed of the train in m/s?
Practice 3easy
A train 200 metres long passes another train 150 metres long moving in the same direction. Train A travels at 80 km/h and Train B travels at 50 km/h. How long will it take for Train A to completely pass Train B?
Practice 4easy
A train travels 360 km in 6 hours. If it increases its speed by 20 km/h, how long will it take to cover the same distance?
Practice 5easy
A train travels 240 km in 4 hours at a constant speed. What is the speed of the train in km/h?
Practice 6easy
A train covers 180 metres in 9 seconds. How long will it take to cover 400 metres at the same speed?
Practice 7medium
Train A of length 150 m crosses a stationary platform in 15 seconds. Train B of length 100 m travels at twice the speed of Train A. How long will Train B take to cross the same platform?
Practice 8medium
A train travels 240 km in 4 hours. If the train increases its speed by 20%, how much distance will it cover in 5 hours at the new speed?
Practice 9medium
Train P (length 120 m) and Train Q (length 80 m) are moving in the same direction on parallel tracks. Train P travels at 90 km/h and Train Q at 54 km/h. How many seconds will it take for Train P to completely overtake Train Q?
Practice 10medium
Two trains start simultaneously from stations P and Q, which are 360 km apart. Train X travels from P towards Q at 60 km/h, and Train Y travels from Q towards P at 40 km/h. After how many hours will they meet?
Practice 11medium
A train 200 m long is running at 72 km/h. How long will it take to pass a man standing on the platform?
Practice 12hard
Train A and Train B start simultaneously from stations P and Q respectively, which are 480 km apart. Train A travels towards Q at 60 km/h, while Train B travels towards P at 40 km/h. After how many hours will they meet, and at what distance from station P?
60-Second Revision — Trains
Remember: Pole crossing uses only train length, platform crossing adds platform length
Formula: Speed conversion km/hr to m/s multiply by 5/18
Trap: Always check if crossing pole or platform - different distance calculations
Shortcut: 72 km/hr = 20 m/s conversion for quick calculations
Relative speed: Add for opposite direction, subtract for same direction
Two trains: Total distance = Length1 + Length2, use relative speed
Platform trick: Time difference method gives platform length directly