Question

18. A copper sphere of radius 3 cm is beaten and drawin into
a wire of diameter 0.2 cm. The length of the wire is
(a) 24 m
(b) 27 m
(c) 30 m
(d) 36 m

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Answer 1

radius = half of diameter

= 1/2 × 0.2

= 0.1

circumference of circle = 2πr

= 2×22/7×0.1

= 0.63

Answer 2

Given :-

• Radius of copper sphere (r) = 3 cm
• Diameter of copper wire (d) = 0.2 cm
• Therefore, Radius of copper wire (R) = 0.1 cm

To Find :-

• The length of the wire = ?

Answer :-

• The length of the wire is 36 m

Explaination :-

→ Volume of wire = Volume of sphere

→ πR²h = 4/3 πr³

Canceling π from both the sides we get :

→ (0.1)²h = 4/3 (3)³

→ (0.01)(h) = 4/3 (27)

→ (0.01)(h) = 4 × 9

→ h = (4 × 9)/0.01

→ h = 36/0.01

→ h = 3600 cm

Converting cm into m we get :-

→ 3600 cm = 36 m

Hence, h = 36 m

Therefore,the Length of the wire is (d) 36 m.