Two trains traveling towards one another on a straight track are 300m apart when the engineers on both trains become aware of the impending

Question

Two trains traveling towards one another on a straight track are 300m apart when the engineers on both trains become aware of the impending Collision and hit their brakes. The eastbound train, initially moving at 97.0 km/h Slows down at 3.50ms^2. The westbound train, initially moving at 127 km/h slows down at 4.20 m/s^2. What is the distance between them once they stop (express your answer to the two significant figures)

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Thiên Di 5 years 2021-07-30T20:26:23+00:00 1 Answers 170 views 0

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  1. thanhha
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    2021-07-30T20:27:28+00:00
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    Answer:

    48 m

    Explanation:

    Two trains traveling towards one another on a straight track are 300m apart when the engineers on both trains become aware of the impending Collision and hit their brakes. The eastbound train, initially moving at 97.0 km/h Slows down at 3.50ms^2. The westbound train, initially moving at 127 km/h slows down at 4.20 m/s^2.

    The eastbound train

    First convert km/h to m/s

    (97 × 1000)/3600

    97000/3600

    26.944444 m/s

    As the train is decelerating, final velocity V = 0 and acceleration a will be negative. Using third equation of motion

    V^2 = U^2 – 2as

    O = 26.944^2 – 2 × 3.5 S

    726 = 7S

    S = 726/7

    S1 = 103.7 m

    The westbound train

    Convert km/h to m/s

    (127×1000)/3600

    127000/3600

    35.2778 m/s

    Using third equation of motion

    V^2 = U^2 – 2as

    0 = 35.2778^2 – 2 × 4.2 × S

    1244.52 = 8.4S

    S = 1244.52/8.4

    S2 = 148.2 m

    S1 + S2 = 103.7 + 148.2 = 251.86

    The distance between them once they stop will be

    300 – 251.86 = 48.14 m

    Therefore, the distance between them once they stop is 48 metres approximately.

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