Speed, Time and Distance
 Two trains of equal length are running on parallel lines in the same direction at 46 km/h and 36 km/h. The faster train passes, the slower train in 36 seconds. The length of each train is :

 82 m
 50 m
 80 m
 72 m

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Let the length of each train be x metre.
Relative speed = 46 – 36 = 10 kmph= 10 × 5 metre/second 18 = 25 metre/second 9 ∴ 2x = 36 (25/9) ⇒ 2x = 36 × 25 = 100 9
⇒ x = 50 metreCorrect Option: B
Let the length of each train be x metre.
Relative speed = 46 – 36 = 10 kmph= 10 × 5 metre/second 18 = 25 metre/second 9 ∴ 2x = 36 (25/9) ⇒ 2x = 36 × 25 = 100 9
⇒ x = 50 metre
 A bus moving at a speed of 45 km/hr overtakes a truck 150 metres ahead going in the same direction in 30 seconds. The speed of the truck is

 27 km/hr
 24 km/hr
 25 km/hr
 28 km/hr

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Let the speed of the truck be x kmph
Relative speed of the bus = (45  x) kmph∴ Time = Distance Relative speed ⇒ 30 60 × 60 = 150 1000 (45 − x) ⇒ 1 = 15 120 100(45 − x) ⇒ 1 = 3 ⇒ (45 − x) = 18 6 (45 − x)
⇒ x = 45 – 18 = 27 kmphCorrect Option: A
Let the speed of the truck be x kmph
Relative speed of the bus = (45  x) kmph∴ Time = Distance Relative speed ⇒ 30 60 × 60 = 150 1000 (45 − x) ⇒ 1 = 15 120 100(45 − x) ⇒ 1 = 3 ⇒ (45 − x) = 18 6 (45 − x)
⇒ x = 45 – 18 = 27 kmph
 Two trains travel in the same direction at the speed of 56 km/h and 29 km/h respectively. The faster train passes a man in the slower train in 10 seconds. The length of the faster train (in metres) is

 100
 80
 75
 120

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Relative speed = 56 – 29 = 27 kmph
= 27 × 5 = 15 m/sec 18 2
∴ Distance covered in 10 seconds= 15 × 10 = 75 m 2
Hence, length of train = 75 m.Correct Option: C
Relative speed = 56 – 29 = 27 kmph
= 27 × 5 = 15 m/sec 18 2
∴ Distance covered in 10 seconds= 15 × 10 = 75 m 2
Hence, length of train = 75 m.
 Two trains are running with speed 30 km/hr and 58 km/hr in the same direction. A man in
the slower train passes the faster train in 18 seconds. The length (in metres) of the faster train is :

 70
 100
 128
 140

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Relative speed = (58 – 30) km/hr
= 28 × 5 m/sec. 18 = 70 m/sec. 9 ∴ Length of train = 70 × 18 9
= 140 metresCorrect Option: D
Relative speed = (58 – 30) km/hr
= 28 × 5 m/sec. 18 = 70 m/sec. 9 ∴ Length of train = 70 × 18 9
= 140 metres
 A constable follows a thief who is 200 m ahead of the constable. If the constable and the thief run at speed of 8 km/hour and 7 km/hour respectively, the constable would catch the thief in

 10 minutes
 12 minutes
 15 minutes
 20 minutes

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The constable and thief are running in the same direction
∴ Their relative speed = 8 – 7 = 1km.= 1 × 5 m/sec. 18 ∴
Required time =200 5 18 = 200 × 18 = 720 sec 5 = 720 minutes = 12 minutes 60 Correct Option: B
The constable and thief are running in the same direction
∴ Their relative speed = 8 – 7 = 1km.= 1 × 5 m/sec. 18 ∴
Required time =200 5 18 = 200 × 18 = 720 sec 5 = 720 minutes = 12 minutes 60