Speed, Time and Distance
- A passenger train 150m long is travelling with a speed of 36 km/ hr. If a man is cycling in the direction of train at 9 km/hr., the time taken by the train to pass the man is
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Relative speed of train
= (36 – 9) kmph = 27 kmph= 27 × 5 m/sec 18 = 15 m/sec 2 ∴ Required time = Length of the train Relative speed = 150 × 2 = 20 seconds 15 Correct Option: D
Relative speed of train
= (36 – 9) kmph = 27 kmph= 27 × 5 m/sec 18 = 15 m/sec 2 ∴ Required time = Length of the train Relative speed = 150 × 2 = 20 seconds 15
- Buses start from a bus terminal with a speed of 20 km/hr at intervals of 10 minutes. What is the speed of a man coming from the opposite direction towards the bus terminal if he meets the buses at intervals of 8 minutes?
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Distance covered in 10 minutes at 20kmph = distance covered in 8 minutes at (20 + x )
kmph⇒ 20 × 10 = 8 (20 + x ) 60 60
⇒ 200 = 160 + 8x
⇒ 8x = 40⇒ x = 40 = 5 kmph 8 Correct Option: C
Distance covered in 10 minutes at 20kmph = distance covered in 8 minutes at (20 + x )
kmph⇒ 20 × 10 = 8 (20 + x ) 60 60
⇒ 200 = 160 + 8x
⇒ 8x = 40⇒ x = 40 = 5 kmph 8
- A train, 300m long, passed a man, walking along the line in the same direction at the rate of 3 km/hr in 33 seconds. The speed of the train is
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If the speed of the train be x kmph, then relative speed = (x – 3) kmph.
or (x – 3) × 5 m/sec 18 ∴ 300 = 33 (x − 3) × 5 18
⇒ 5400 = 33 × 5 (x – 3)
⇒ 360 = 11 (x – 3)
⇒ 11x – 33 = 360⇒ x = 393 = 35 8 kmph 11 11 Correct Option: D
If the speed of the train be x kmph, then relative speed = (x – 3) kmph.
or (x – 3) × 5 m/sec 18 ∴ 300 = 33 (x − 3) × 5 18
⇒ 5400 = 33 × 5 (x – 3)
⇒ 360 = 11 (x – 3)
⇒ 11x – 33 = 360⇒ x = 393 = 35 8 kmph 11 11
- A train, 240 m long crosses a man walking along the line in opposite direction at the rate of 3 kmph in 10 seconds. The speed of the train is
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If the speed of train be x kmph then,
Its relative speed = (x + 3) kmph∴ Time = Length of the train Relative Speed ⇒ 10 3600 240 = 1000 x + 3 = 240 1000(x + 3)
⇒ x + 3 = 86.4
⇒ x = 83.4 kmphCorrect Option: C
If the speed of train be x kmph then,
Its relative speed = (x + 3) kmph∴ Time = Length of the train Relative Speed ⇒ 10 3600 240 = 1000 x + 3 = 240 1000(x + 3)
⇒ x + 3 = 86.4
⇒ x = 83.4 kmph
- Two trains of equal length, running in opposite directions, pass a pole in 18 and 12 seconds. The trains will cross each other in
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Let the length of each train be x metre.
Speed of first train = x m/sec 18 Speed of second train = x m/sec 12
When both trains cross each other, time taken= 2x x + x 18 12 = 2x 2x + 3x 36 = 2x × 36 5x = 72 = 14.4 seconds 5 Correct Option: A
Let the length of each train be x metre.
Speed of first train = x m/sec 18 Speed of second train = x m/sec 12
When both trains cross each other, time taken= 2x x + x 18 12 = 2x 2x + 3x 36 = 2x × 36 5x = 72 = 14.4 seconds 5
