Question

13. On the curved surface of the axis of a globe with the length of 14 cm radius, two circular
holes are made each of which has the length of radius 0.7 cm. Let us calculate the area of
metal sheet surrounding its curved surface.​

Answer 1

Given:

A Globe i.e. sphere with radius 14 cm and two holes each of radius 0.7 cm.

To Find:

Area of metal sheet required for globe.

Solution:

It is given that, globe has radius of 14 cm

Now, Surface Area of sphere = 4π$r^{2}$

Surface Area of sphere = $4$ × $\frac{22}{7}$ × 14 × 14

Surface Area of sphere = 2464 $cm^{2}$

Now, Area of circular hole = π$r^{2}$

Area of circular hole = $\frac{22}{7}$ × $0.7$ × $0.7$ = $1.54$  $cm^{2}$

Now,

Area of metal sheet required for globe = Surface area of sphere - 2 × area of circular hole

Area of metal sheet required for globe = 2464 - 3.08 = 2460.92 $cm^{2}$

Hence,  2460.92 $cm^{2}$ of metal sheet is required for globe.