Advertisements
Advertisements
Question
Find the surface area of a sphere of diameter 3.5 m.
`["Assume "pi=22/7]`
Advertisements
Solution
Radius (r) of sphere = `"Diameter"/2`
= `3.5/2`
= 1.75 m
Surface area of sphere = 4πr2
= `[4 xx 22/7 xx (1.75)^2] m^2`
= 38.5 m2
Therefore, the surface area of the sphere having diameter 3.5 m is 38.5 m2.
APPEARS IN
RELATED QUESTIONS
The surface area of a solid metallic sphere is 2464 cm2. It is melted and recast into solid right circular cones of radius 3.5 cm and height 7 cm. Calculate:
- the radius of the sphere.
- the number of cones recast. (Take π = `22/7`)
A hollow sphere of internal and external radii 6 cm and 8 cm respectively is melted and recast into small cones of base radius 2 cm and height 8 cm. Find the number of cones.
Find the surface area of a sphere of radius 5.6 cm.
Find the surface area of a sphere of diameter 21 cm.
Find the surface area of a sphere of diameter 3.5 cm.
A wooden toy is in the form of a cone surmounted on a hemisphere. The diameter of the base
of the cone is 16 cm and its height is 15 cm. Find the cost of painting the toy at Rs. 7 per 100
`cm^2`.
The volume of one sphere is 27 times that of another sphere. Calculate the ratio of their :
- radii,
- surface areas.
Metallic spheres of radii 6 cm, 8 cm and 10 cm respectively are melted and recasted into a single solid sphere. Taking π = 3.1, find the surface area of the solid sphere formed.
A hollow sphere of internal and external diameter 4 cm and 8 cm respectively is melted into a cone of base diameter 8 cm. Find the height of the cone.
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.
The total surface area of a hemisphere of radius r is
The ratio of the total surface area of a sphere and a hemisphere of same radius is
If the surface area of a sphere is 144π m2, then its volume (in m3) is
If the surface area of a sphere is 2826 cm2 then find its volume. ( π= 3.14)
Find the surface area of a sphere, if its volume is 38808 cubic cm. `(π = 22/7)`
Find the radius of a sphere whose surface area is equal to the area of the circle of diameter 2.8 cm
