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A train of length 180 metres crosses a tree in 15 seconds and crosses another train of the same length travelling in opposite direction in 20 seconds. What is the speed (in km/hr) of the second train?
- a)21.6
- b)6
- c)33.4
- d)36.6
Correct answer is option 'A'. Can you explain this answer?
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Verified Answer
A train of length 180 metres crosses a tree in 15 seconds and crosses ...
Time taken to cross the tree = Length of train/Speed of train
⇒ Speed of train = 180/15 = 12 m/sec.
Let the speed of the second train be ‘x’ m/sec.
∵ The trains are moving in opposite directions, hence, their relative speed is the sum of their individual speeds
⇒ Relative speed = x + 12
Now,
Time taken to cross each other = Sum of lengths of trains/Relative speed
⇒ 20 = (180 + 180)/(x + 12)
⇒ x + 12 = 360/20
⇒ x = 18 - 12 = 6 m/sec.
∴ Speed of second train = 6 × 18/5 = 21.6 km/hr.
⇒ Speed of train = 180/15 = 12 m/sec.
Let the speed of the second train be ‘x’ m/sec.
∵ The trains are moving in opposite directions, hence, their relative speed is the sum of their individual speeds
⇒ Relative speed = x + 12
Now,
Time taken to cross each other = Sum of lengths of trains/Relative speed
⇒ 20 = (180 + 180)/(x + 12)
⇒ x + 12 = 360/20
⇒ x = 18 - 12 = 6 m/sec.
∴ Speed of second train = 6 × 18/5 = 21.6 km/hr.
Most Upvoted Answer
A train of length 180 metres crosses a tree in 15 seconds and crosses ...
Given:
- Length of the train = 180 meters
- Time taken to cross a tree = 15 seconds
- Time taken to cross another train in the opposite direction = 20 seconds
To find:
- Speed of the second train in km/hr
Explanation:
To find the speed of the second train, we need to calculate the relative speed of the two trains first.
Let's assume the speed of the first train is v1 m/s and the speed of the second train is v2 m/s.
When the first train crosses the tree, it covers its own length of 180 meters in 15 seconds. So, the speed of the first train can be calculated as:
v1 = 180/15 = 12 m/s
When the first train crosses the second train, they both cover their own lengths of 180 meters each in 20 seconds. So, the relative speed of the two trains can be calculated as:
Relative speed = Total distance/Total time
Relative speed = (180 + 180)/20 = 360/20 = 18 m/s
Now, we can calculate the speed of the second train by subtracting the speed of the first train from the relative speed:
v2 = Relative speed - v1
v2 = 18 - 12 = 6 m/s
To convert the speed from m/s to km/hr, we multiply by (18/5):
v2 = 6 * (18/5) = 21.6 km/hr
Therefore, the speed of the second train is 21.6 km/hr.
Answer:
Option A) 21.6
- Length of the train = 180 meters
- Time taken to cross a tree = 15 seconds
- Time taken to cross another train in the opposite direction = 20 seconds
To find:
- Speed of the second train in km/hr
Explanation:
To find the speed of the second train, we need to calculate the relative speed of the two trains first.
Let's assume the speed of the first train is v1 m/s and the speed of the second train is v2 m/s.
When the first train crosses the tree, it covers its own length of 180 meters in 15 seconds. So, the speed of the first train can be calculated as:
v1 = 180/15 = 12 m/s
When the first train crosses the second train, they both cover their own lengths of 180 meters each in 20 seconds. So, the relative speed of the two trains can be calculated as:
Relative speed = Total distance/Total time
Relative speed = (180 + 180)/20 = 360/20 = 18 m/s
Now, we can calculate the speed of the second train by subtracting the speed of the first train from the relative speed:
v2 = Relative speed - v1
v2 = 18 - 12 = 6 m/s
To convert the speed from m/s to km/hr, we multiply by (18/5):
v2 = 6 * (18/5) = 21.6 km/hr
Therefore, the speed of the second train is 21.6 km/hr.
Answer:
Option A) 21.6
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A train of length 180 metres crosses a tree in 15 seconds and crosses another train of the same length travelling in opposite direction in 20 seconds. What is the speed (in km/hr) of the second train?a)21.6b)6c)33.4d)36.6Correct answer is option 'A'. Can you explain this answer?
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A train of length 180 metres crosses a tree in 15 seconds and crosses another train of the same length travelling in opposite direction in 20 seconds. What is the speed (in km/hr) of the second train?a)21.6b)6c)33.4d)36.6Correct answer is option 'A'. Can you explain this answer? for Defence 2024 is part of Defence preparation. The Question and answers have been prepared according to the Defence exam syllabus. Information about A train of length 180 metres crosses a tree in 15 seconds and crosses another train of the same length travelling in opposite direction in 20 seconds. What is the speed (in km/hr) of the second train?a)21.6b)6c)33.4d)36.6Correct answer is option 'A'. Can you explain this answer? covers all topics & solutions for Defence 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for A train of length 180 metres crosses a tree in 15 seconds and crosses another train of the same length travelling in opposite direction in 20 seconds. What is the speed (in km/hr) of the second train?a)21.6b)6c)33.4d)36.6Correct answer is option 'A'. Can you explain this answer?.
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