46. A train is running at a speed of 90 km/hr. If it crosses a signal in 10 sec., the length of the train (in metres) is

1. 1. 150

   
   
   

   2. 324

   
   
   

   3. 900

   
   
   

   4. 250

   
   
   

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1. View Hint View Answer Discuss in Forum

   Speed of train = 90 kmph
   

   =		90 × 5		metre/second
   		18

   
   = 25 metre/second
   If the length of the train be x then,
   

   Speed of train =	Length of train
   	Time taken in crossing the signal

   
   

   ⇒  25 =	x
   	10

   
   ⇒  x = 250 metre

   Correct Option: D

   Speed of train = 90 kmph
   

   =		90 × 5		metre/second
   		18

   
   = 25 metre/second
   If the length of the train be x then,
   

   Speed of train =	Length of train
   	Time taken in crossing the signal

   
   

   ⇒  25 =	x
   	10

   
   ⇒  x = 250 metre

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47. A train 100 metres long meets a man going in opposite direction at 5 km/hr and

    passes him in 7	1	seconds.
    	5

    What is the speed of the train (in km/hr) ?

1. 1. 45 km/hr

   
   
   

   2. 60 km/hr

   
   
   

   3. 55 km/hr

   
   
   

   4. 50 km/hr

   
   
   

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1. View Hint View Answer Discuss in Forum

   Let speed of train be x kmph
   Relative speed = (x + 5) kmph
   

   Length of train =	100	km
   	1000

   
   

   =	1	km
   	10

   
   

   	1
   ∴	10
   	x + 5

   
   

   =	36
   	5 × 60 × 60

   
   

   ⇒	1	=	1
   	10(x +5)		500

   
   ⇒  x + 5 = 50
   ⇒  x = 45 kmph

   Correct Option: A

   Let speed of train be x kmph
   Relative speed = (x + 5) kmph
   

   Length of train =	100	km
   	1000

   
   

   =	1	km
   	10

   
   

   	1
   ∴	10
   	x + 5

   
   

   =	36
   	5 × 60 × 60

   
   

   ⇒	1	=	1
   	10(x +5)		500

   
   ⇒  x + 5 = 50
   ⇒  x = 45 kmph

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48. A train, 120 m long, takes 6 seconds to pass a telegraph post; the speed of train is

1. 1. 72 km/hr

   
   
   

   2. 62 km/hr

   
   
   

   3. 55 km/hr

   
   
   

   4. 85 km/hr

   
   
   

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1. View Hint View Answer Discuss in Forum

   Speed of train =	Length of train
   	Time taken in crossing the pole

   
   

   =	120	= 20 m/sec
   	6

   
   

   = 20 ×	18	= 72 kmph
   	5

   Correct Option: A

   Speed of train =	Length of train
   	Time taken in crossing the pole

   
   

   =	120	= 20 m/sec
   	6

   
   

   = 20 ×	18	= 72 kmph
   	5

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49. A train 300 m long is running with a speed of 54 km/hr. In what time will it cross a telephone pole?

1. 1. 20 seconds

   
   
   

   2. 15 seconds

   
   
   

   3. 17 seconds

   
   
   

   4. 18 seconds

   
   
   

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1. View Hint View Answer Discuss in Forum

   Speed of train = 54 kmph
   

   =		54 × 5		m/sec = 15 m/sec
   		18

   
   

   Required time =	Length of trains
   	Speed of train

   
   

   =	300	= 20 seconds
   	15

   Correct Option: A

   Speed of train = 54 kmph
   

   =		54 × 5		m/sec = 15 m/sec
   		18

   
   

   Required time =	Length of trains
   	Speed of train

   
   

   =	300	= 20 seconds
   	15

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50. A train 180 metres long is running at a speed of 90 km/h. How long will it take to pass a post ?

1. 1. 8.2 secs

   
   
   

   2. 7.8 secs

   
   
   

   3. 8 secs

   
   
   

   4. 7.2 secs

   
   
   

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1. View Hint View Answer Discuss in Forum

   Speed of train = 90 kmph
   

   =		90 ×	5		m/sec.
   			18

   
   = 25 m/sec.
   When a train crosses a post, it covers a distance equal to its own length.
   

   ∴  Required time =	Distance
   	Speed

   
   

   =	180	= 7.2 seconds
   	25

   Correct Option: D

   Speed of train = 90 kmph
   

   =		90 ×	5		m/sec.
   			18

   
   = 25 m/sec.
   When a train crosses a post, it covers a distance equal to its own length.
   

   ∴  Required time =	Distance
   	Speed

   
   

   =	180	= 7.2 seconds
   	25

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