Question

a train of length 120 m is travelling at 144km/h. it is passed under a bridge of width 20m. find the time taken for the whole train to pass under the bridge. give your answer in seconds

Answer 1

Answer:

Speed of train = 144km/h = 2400m/s

length of train = 120m

length of bridge = 20m

Distance to be covered = 20+120 = 140m

v = d/t

t = d/v

 = 140m/2400m/s = 7/12 second

Answer 2

Given: A train of length 120 m is travelling at 144km/h. It moves through a bridge of width 20m.

To find: The time taken for the whole train to move through the bridge.

Solution:

• Since the length of the train is 120 m and the width of the bridge is 20m, the distance to be travelled by the train is calculated as,

        $120 m + 20 m = 140 m$

• The speed is given as 144kmh⁻¹, so it shall be converted to ms⁻¹ as follows,

        $\frac{144 * 1000}{3600} = 40ms^{-1}$

• Speed is given by the formula,

        $s = \frac{d}{t}$

• Here, d is the distance travelled by the train and t is the time taken.

        $40ms^{-1} = \frac{140m}{t}$

         $t = 3.5s$

Therefore, the time taken for the whole train to move through the bridge is 3.5 s.