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. 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. 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. 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. 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. 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