Advertisements
Advertisements
Question
Find the volume and surface area of a sphere of diameter 21 cm.
Advertisements
Solution
Diameter of sphere = 21 cm
∴ Radius of sphere = `21/2` cm
∴ Surface area of sphere = 4πr2
= `4 xx 22/7 xx 21/2 xx 21/2`
= 1386 cm2
Volume of sphere = `4/3`πr3
= `4 xx 22/7 xx 21/2 xx 21/2 xx 21/2`
= 4851 cm3.
RELATED QUESTIONS
Find the maximum volume of a cone that can be carved out of a solid hemisphere of radius r cm.
A largest sphere is to be carved out of a right circular cylinder of radius 7 cm and height 14 cm. Find the volume of the sphere.
The cross-section of a tunnel is a square of side 7 m surmounted by a semi-circle as shown in the adjoining figure. The tunnel is 80 m long.
Calculate:
- its volume,
- the surface area of the tunnel (excluding the floor) and
- its floor area.
Find the radius of a sphere whose surface area is 154 cm2.
If the surface area of a sphere is 144π m2, then its volume (in m3) is
If a solid sphere of radius 10 cm is moulded into 8 spherical solid balls of equal radius, then the surface area of each ball (in sq.cm) is
If a sphere is inscribed in a cube, then the ratio of the volume of the sphere to the volume of the cube is
The model of a building is constructed with the scale factor 1 : 30.
(i) If the height of the model is 80 cm, find the actual height of the building in meters.
(ii) If the actual volume of a tank at the top of the building is 27m3, find the volume of the tank on the top of the model.
Find the volume of a sphere, if its surface area is 154 sq.cm.
The radius of a sphere increases by 25%. Find the percentage increase in its surface area
