Question

    A solid metallic sphere of radius 3 cm is melted and

    drawn into a wire of thickness 4 mm. What is the length of the wire (in m)?
    A 9.25 Correct Answer Incorrect Answer
    B 7.5 Correct Answer Incorrect Answer
    C 9 Correct Answer Incorrect Answer
    D 8 Correct Answer Incorrect Answer

    Solution

    r = radius of the base of the cylinder and radius of the sphere h = length of the height of the cylinder Thickness 4 mm i.e. diameter So, radius = 2 mm Now, 3 cm = 30 mm According to the question, Volume of the sphere = Volume of the wire (4/3) πr3 = πr2 h (4/3) × (30)3 =4h 9000 = h So, the length of the wire = 9000 mm But here we have asked the length of the wire in m. So, length = 9000/1000 = 9 m [ ∵ 1 m = 1000 mm]

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