Discussion
A train travelling at 48 kmph completely crosses another train having half its length and travelling in opposite direction at 42 kmph, in 12 seconds. It also passes a railway platform in 45 seconds. The length of the platform is
Answer: A
Trains moving in the same direction close at the difference of their speeds; in opposite directions, at the sum.
Let the first train be \( L \) long; the second is \( \tfrac{L}{2} \).
\[ \text{relative speed} = 48 + 42 = 90 \text{ kmph} = 25 \text{ m/s} \]
\[ L + \frac{L}{2} = 25 \times 12 = 300 \quad\Longrightarrow\quad 1.5L = 300 \]
\[ L = 200 \text{ m} \]
Crossing the platform, the train travels alone at 48 kmph \( = \tfrac{40}{3} \) m/s:
\[ 200 + P = \frac{40}{3} \times 45 = 600 \quad\Longrightarrow\quad P = 400 \text{ m} \]
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