-
A copper sphere of radius 3 cm is beaten and drawn into a wire of diameter 0.2 cm. The length of the wire is :
-
- 9 m
- 12 m
- 18 m
- 36 m
- 9 m
Correct Option: D
| Volume of copper sphere = | πr³ = | × | × 3 × 3 × 3 | |||
| 3 | 3 | 7 |
| = | cm³ | |
| 7 |
Radius of the wire = 0.1 cm
The wire can be treated as a solid cylinder.
Let its length be h cm.
| ∴ π × (0.1)² × h = | cm³ | |
| 7 |
| ⇒ h = 36 × | × | × | = 3600 cm = 36 m. | |||
| 7 | 22 | 0.01 |
∴ Length of the wire = 36 metres.
