On a 100km track , a train travels the first 30km with a speed of 30km/h . How fast the train travel the next 70 km if the average speed for

Question

On a 100km track , a train travels the first 30km with a speed of 30km/h . How fast the train travel the next 70 km if the average speed for the entire journey is 40km/h?

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Calantha 3 years 2021-08-06T18:12:05+00:00 1 Answers 23 views 0

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  1. Eirian
    0
    2021-08-06T18:13:15+00:00
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    Solution :-

    Given :

    Distance 1 = 30 km

    Distance 2 = 70 km

    We know that speed = distance/time

    and, Average speed = total distance/total time taken

    When the train acquired a speed of 30 km/hr, the time taken = 30/30 = 1 hour

    Average speed = 9distance 1 + distance 2)/(time 1 + time 2)

    AS time 2 or t2 is time taken for the second part of the journey of 70 km

    ⇒ 40 = 100/(1 + t2)

    ⇒ 40 + 40t2 = 100

    ⇒ 40t2 = 100 – 40

    ⇒ 40t2 = 60

    ⇒ t2 = 60/40

    ⇒ t2 = 1.5

    So, t2 or time taken to travel the second part of the journey is 1.5 hours.

    Speed of the second part of the journey = distance 2/time 2

    ⇒ 70/1.5

    ⇒ 46.666 km/hr or 46.7 km/hr.

    Hence the answer is = 46.666 km/hr or 46.7 km/hr.

    Hope it helped u if yes mark me BRAINLIEST!

    Tysm!

    🙂

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