A solid copper sphere of radius 9 cm is hammered and moulded into a wire of radius 2 cm. What is the length of this wire?
Show answer & explanation
Correct answer: D
Explanation
The correct answer is Option 4 i.e. 243 cm.
Given:
Radius of wire(cylinder) = 2 cm
Radius of sphere = 9 cm
Formula used:
Volume of cylinder = πr2h
Volume of sphere = (4/3)πr3
Calculations:
Let the length of be the wire be h.
According to the question;
Volume of cylinder = Volume of sphere
⇒ π × 2 × 2 × h = (4/3) × π × 9 × 9 × 9
⇒ h = 3 × 9 × 9 = 243 cm