Multiple choice

A copper wire which lengths is 36 m. and diameter 2 mm, melted in the form of a sphere. Find the radius of sphere.

  1. 2.5 cm.

  2. 3 cm.

  3. 3.5 cm.

  4. 4 cm.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Copper wire is cylindrical. Length = 36 m = 3600 cm, diameter = 2 mm, so radius = 1 mm = 0.1 cm. Volume = πr²h = π × 0.01 × 3600 = 36π cm³. This forms a sphere with volume (4/3)πR³ = 36π, so R³ = (36π × 3)/(4π) = 27, R = 3 cm. Option B is correct because the sphere's radius calculates to 3 cm.

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