Discussion
Two trains of equal length are running on parallel lines in the same direction at 46 km/ hr and 36 km/ hr. The faster train passes the slower train in 36 seconds. The length of each train is:
Answer: D
Each train is 50 m long.
Moving the same way, the faster train gains at the difference of the speeds, and to pass completely it must cover both lengths, \(2L\):
\[ \begin{aligned} v &= 46 - 36 = 10\ \text{km/h} \\ &= 10 \times \tfrac{5}{18} = \tfrac{25}{9}\ \text{m/s} \\ 2L &= \tfrac{25}{9} \times 36 = 100\ \text{m} \\ L &= 50\ \text{m} \end{aligned} \]
100 m is the combined length, so 80 m and 72 m do not fit. 36 m comes from treating the relative speed as 1 m/s. Adding the speeds would be right only for trains moving in opposite directions.
Post your comment
Please log in or register to post a comment.
Examination Categories
- SSC Exams
- Banking Exams
- Teaching Exams
- Civil Services Exams
- Railways Exams
- Engineering Recruitment Exams
- Defence Exams
- State Government Exams
- Police Exams
- Insurance Exams
- Nursing Exams
- Other Government Exams
- NRA CET
- PG Entrance Exams
- Campus Placement
- MBA Entrance Exams
- CUET and UG Entrance
- Judiciary Exams
- Regulatory Body Exams
- Software Development