Advertisements
Advertisements
Question
Find the surface area of a sphere of diameter 3.5 cm.
Advertisements
Solution
Diameter = 3.5cm
Radius = `(3. 5cm)/2 -1.75 cm.`
∴ Surface area = `4πr^2 - 4 × 22/7 × (3.5)/(2^2)`
= 38.5 cm 2
RELATED QUESTIONS
A hemispherical bowl is made of steel, 0.25 cm thick. The inner radius of the bowl is 5 cm. Find the outer curved surface area of the bowl.
`["Assume "pi = 22/7]`
Find the total surface area of a hemisphere and a solid hemisphere each of radius 10 cm.
(Use ЁЭЬЛ = 3.14)
The diameter of the moon is approximately one fourth of the diameter of the earth. Find the
ratio of their surface areas.
The volume of a sphere is 38808 cm3; find its diameter and the surface area.
A solid sphere of radius 15 cm is melted and recast into solid right circular cones of radius 2.5 cm and height 8 cm. Calculate the number of cones recast.
The total area of a solid metallic sphere is 1256 cm2. It is melted and recast into solid right circular cones of radius 2.5 cm and height 8 cm. Calculate :
- the radius of the solid sphere.
- the number of cones recast. [Take π = 3.14]
What is the least number of solid metallic spheres, each of 6 cm diameter, that should be melted and recast to form a solid metal cone whose height is 45 cm and diameter 12 cm?
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.
How many spherical bullets can be made out of a solid cube of lead whose edge measures 44 cm, each bullet being 4 cm in diameter?
If a sphere of radius 2r has the same volume as that of a cone with circular base of radius r, then find the height of the cone.
If a sphere is inscribed in a cube, find the ratio of the volume of cube to the volume of the sphere.
The ratio of the total surface area of a sphere and a hemisphere of same radius is
The largest sphere is cut off from a cube of side 6 cm. The volume of the sphere will be
A cylindrical rod whose height is 8 times of its radius is melted and recast into spherical balls of same radius. The number of balls will be
If a sphere is inscribed in a cube, then the ratio of the volume of the sphere to the volume of the cube is
If a solid sphere of radius r is melted and cast into the shape of a solid cone of height r, then the radius of the base of the cone is
Find the surface area and volume of sphere of the following radius. (π = 3.14 )
9 cm
The radius of a sphere is 9 cm. It is melted and drawn into a wire of diameter 2 mm. Find the length of the wire in metre.
Find the length of the wire of diameter 4 m that can be drawn from a solid sphere of radius 9 m.
A solid metallic cylinder has a radius of 2 cm and is 45 cm tall. Find the number of metallic spheres of diameter 6 cm that can be made by recasting this cylinder .
From a rectangular solid of metal 42 cm by 30 cm by 20 cm, a conical cavity of diameter 14 cm and depth 24 cm is drilled out. Find: the volume of remaining solid
A certain number of metallic cones, each of radius 2 cm and height 3 cm are melted and recast into a solid sphere of radius 6 cm. Find the number of cones used.
There is a ratio 1: 4 between the surface area of two spheres, find the ratio between their radius.
A sphere cut out from a side of 7 cm cubes. Find the volume of this sphere?
The internal and external diameters of a hollow hemispherical vessel are 20 cm and 28 cm respectively. Find the cost to paint the vessel all over at тВ╣ 0.14 per cm2
The total surface area of a hemisphere is how many times the square of its radius
