Speed, Time and Distance


  1. A train passes two bridges of lengths 800 m and 400 m in 100 seconds and 60 seconds
    respectively. The length of the train is :
    1. 80 m
    2. 90 m
    3. 200 m
    4. 150 m

  1. View Hint View Answer Discuss in Forum

    When a train crosses a bridge it covers the distance equal to length of Bridge & its own length
    Let the length of the train be = x

    ∴  Speed of the train =
    x + 800
    m/s
    100

    Since train passes the 800 m bridge in 100 seconds.
    Again, train passes the 400 m bridge in 60 seconds.

    ∴ 
    400 + x
    = 60
    x + 800
    100

    ⇒ 
    (400 + x) × 100
    = 60
    x + 800

    ⇒  40000 + 100x
    = 60x + 48000
    ⇒  100x – 60x = 48000 – 40000
    ⇒  40x = 8000
    ∴  x =
    8000
    = 200m
    40

    Correct Option: C

    When a train crosses a bridge it covers the distance equal to length of Bridge & its own length
    Let the length of the train be = x

    ∴  Speed of the train =
    x + 800
    m/s
    100

    Since train passes the 800 m bridge in 100 seconds.
    Again, train passes the 400 m bridge in 60 seconds.

    ∴ 
    400 + x
    = 60
    x + 800
    100

    ⇒ 
    (400 + x) × 100
    = 60
    x + 800

    ⇒  40000 + 100x
    = 60x + 48000
    ⇒  100x – 60x = 48000 – 40000
    ⇒  40x = 8000
    ∴  x =
    8000
    = 200m
    40


  1. The length 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. View Hint View Answer Discuss in Forum

    Let the length of train be x metre
    Speed = 90 km/hr

    =
    90 × 5
    metre/sec.
    18

    = 25 metre/sec.
    ∴  Distance covered in 60 sec.
    = 25 × 60 = 1500 metres
    Now, according to question,
    2x = 1500
    ∴  x = 750 metre

    Correct Option: C

    Let the length of train be x metre
    Speed = 90 km/hr

    =
    90 × 5
    metre/sec.
    18

    = 25 metre/sec.
    ∴  Distance covered in 60 sec.
    = 25 × 60 = 1500 metres
    Now, according to question,
    2x = 1500
    ∴  x = 750 metre



  1. A man travels some distance at a speed of 12 km/hr and returns at a speed of 9 km/hr. If the total time taken by him is 2 hrs 20 minutes the distance is
    1. 35 km.
    2. 21 km.
    3. 9 km.
    4. 12 km.

  1. View Hint View Answer Discuss in Forum

    Let the required distance be x km.

    Time = 2 hours 20 minutes 2
    1
    hours
    3

    According to the question,
    x
    +
    x
    =
    7
    1293

    ⇒ 
    3x + 4x
    =
    7
    363

    ⇒ 
    7x
    =
    7
    363

    ⇒ x =
    7
    ×
    36
    = 12 km.
    37

    Correct Option: D

    Let the required distance be x km.

    Time = 2 hours 20 minutes 2
    1
    hours
    3

    According to the question,
    x
    +
    x
    =
    7
    1293

    ⇒ 
    3x + 4x
    =
    7
    363

    ⇒ 
    7x
    =
    7
    363

    ⇒ x =
    7
    ×
    36
    = 12 km.
    37


  1. Sound travels at 330 metre per second. The distance (in kilometre) of a thunder cloud when its sound follows the flash after 10 seconds is :
    1. 0.33 km.
    2. 3.3 km.
    3. 33 km.
    4. 33.3 km.

  1. View Hint View Answer Discuss in Forum

    Distance = Speed × Time
    = 330 × 10 = 3300 metre

    =
    3300
    km. = 3.3 km.
    1000

    Correct Option: B

    Distance = Speed × Time
    = 330 × 10 = 3300 metre

    =
    3300
    km. = 3.3 km.
    1000



  1. To cover a certain distance with a speed of 60 km/hr, a train takes 15 hours. If it covers the
    same distance in 12 hours, what will be its speed?
    1. 65 km/h
    2. 70 km/h
    3. 75 km/h
    4. 80 km/h

  1. View Hint View Answer Discuss in Forum

    Distance covered by train in
    15 hours = Speed × Time
    = (60 × 15) km. = 900 km.
    Required speed to cover 900 km.

    in 12 hours =
    900
    = 75 kmph
    12

    Correct Option: C

    Distance covered by train in
    15 hours = Speed × Time
    = (60 × 15) km. = 900 km.
    Required speed to cover 900 km.

    in 12 hours =
    900
    = 75 kmph
    12