Question

    A race track is in the shape of a rectangle with length

    of 80 metres and area of 2400 m2. A car takes 20 seconds to make one lap around the perimeter of this track. If the car and a person whose speed is 5 m/s, started moving at the same time along the perimeter of the track but in opposite directions, then find the distance between the car and the person, 3 seconds before they cross each other.
    A 48 metres Correct Answer Incorrect Answer
    B 38 metres Correct Answer Incorrect Answer
    C 28 metres Correct Answer Incorrect Answer
    D 58 metres Correct Answer Incorrect Answer
    E None of these Correct Answer Incorrect Answer

    Solution

    Area of the track = length of track x breadth of track = 80 x breadth of track = 2400 So, breadth of track = 2400 ÷ 80 = 30 So, perimeter of the track = (80 + 30) x 2 = 220 metres So, speed of the car = (220/20) = 11 m/s Relative speed of the car with respect to the person = 11 + 5 = 16 m/s So, distance between the car and the person, 3 seconds before they cross each other = 16 x 3 = 48 metres

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