## Speed, Time and Distance

#### Speed, Time and Distance

1. A train, 200 metre long, is running at a speed of 54 km/hr. The time in seconds that will be taken by train to cross a 175 metre long bridge is :
1. 12.5
2. 20
3. 25
4. 10

1. Speed of train = 54 kmph

 = 54 × 5 m/sec. 18

= 15 m/sec.
 ∴  Required time = Length of train and bridge Speed of train

 = 200 + 175 seconds 15

 = 375 seconds 15

= 25 seconds

##### Correct Option: C

Speed of train = 54 kmph

 = 54 × 5 m/sec. 18

= 15 m/sec.
 ∴  Required time = Length of train and bridge Speed of train

 = 200 + 175 seconds 15

 = 375 seconds 15

= 25 seconds

1. A train, 500 metre long, running at a uniform speed, passes a station in 35 seconds. If the length of the platform is 221 metre, the speed of the train in km/hr is
1.  72 1 35
2. 74.16
3. 24.76
4. 78.54

1.  Speed of train = Length of platform and train Time taken in crossing

 = 221 + 500 metre/second 35

 = 721 metre/second 35

 = 721 × 18 kmph 35 × 5

= 74.16 kmph

##### Correct Option: B

 Speed of train = Length of platform and train Time taken in crossing

 = 221 + 500 metre/second 35

 = 721 metre/second 35

 = 721 × 18 kmph 35 × 5

= 74.16 kmph

1. The lengths of a train and that of a platform are equal. If with a speed of 90 km/hr the train
crosses the platform in one minute, then the length of the train (in metres) is
1. 500
2. 600
3. 750
4. 900

1. Let, length of train = length of platform = x metre
Speed of train = 90 kmph

 = 90 × 5 m/sec. 18

= 25 m/sec.
 ∴  Speed of train = Length of platform and train Time taken in crossing

 ⇒  25 = 2x ⇒ 2x = 25 × 60 60

 ⇒  x = 25 × 60 = 750 metre 2

##### Correct Option: C

Let, length of train = length of platform = x metre
Speed of train = 90 kmph

 = 90 × 5 m/sec. 18

= 25 m/sec.
 ∴  Speed of train = Length of platform and train Time taken in crossing

 ⇒  25 = 2x ⇒ 2x = 25 × 60 60

 ⇒  x = 25 × 60 = 750 metre 2

1. A moving train passes a platform 50 metre long in 14 seconds and a lamp post in 10 seconds. The speed of the train (in km/h) is :
1. 24
2. 36
3. 40
4. 45

1. Let the length of train be x metre.
When a train crosses a platform, distance covered by it = length of train and platform.

 ∴  Speed of train = x + 50 = x 14 10

 ⇒ x + 50 = x 7 5

⇒  7x = 5x + 250
⇒  7x – 5x = 250
 ⇒ 2x = 250 ⇒ x = 250 = 125 metre 2

 ∴ Speed of train = x 10

 = 125 m./sec. 10

 = 125 × 18 kmph 10 5

= 45 kmph

##### Correct Option: D

Let the length of train be x metre.
When a train crosses a platform, distance covered by it = length of train and platform.

 ∴  Speed of train = x + 50 = x 14 10

 ⇒ x + 50 = x 7 5

⇒  7x = 5x + 250
⇒  7x – 5x = 250
 ⇒ 2x = 250 ⇒ x = 250 = 125 metre 2

 ∴ Speed of train = x 10

 = 125 m./sec. 10

 = 125 × 18 kmph 10 5

= 45 kmph

1. A train 150 metre long takes 20 seconds to cross a platform 450 metre long. The speed of the train in, km per hour, is :
1. 108
2. 100
3. 106
4. 104

1.  Speed of train = length of platform and train Time taken in crossing

 = 450 + 150 m/sec. 20

 = 600 m/sec. 20

 = 30 × 18 kmph 5

= 108 kmph.

##### Correct Option: A

 Speed of train = length of platform and train Time taken in crossing

 = 450 + 150 m/sec. 20

 = 600 m/sec. 20

 = 30 × 18 kmph 5

= 108 kmph.