Advertisements
Advertisements
प्रश्न
Assuming the earth to be a sphere of radius 6370 km, how many square kilo metres is area
of the land, if three-fourth of the earth’s surface is covered by water?
Advertisements
उत्तर
`3^(th) /4`of earth surface is covered by water
∴ `1^(th)/4` earth surface is covered by land
∴ Surface area covered by land `- 1/4 × 4πr^2`
`- 1/4 × 4 × 22/7× 6370^2`
- `127527.4km^2`
APPEARS IN
संबंधित प्रश्न
Find the surface area of a sphere of diameter 21 cm.
`["Assume "pi=22/7]`
Find the radius of a sphere whose surface area is 154 cm2.
`["Assume "pi=22/7]`
A right circular cylinder just encloses a sphere of radius r (see figure). Find
- surface area of the sphere,
- curved surface area of the cylinder,
- ratio of the areas obtained in (i) and (ii).
How many balls each of radius 1 cm can be made by melting a bigger ball whose diameter is 8 cm?
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 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.
A solid rectangular block of metal 49 cm by 44 cm by 18 cm is melted and formed into a solid sphere. Calculate the radius of the sphere.
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 maximum volume of a cone that can be carved out of a solid hemisphere of radius r cm.
If a hollow sphere of internal and external diameters 4 cm and 8 cm respectively melted into a cone of base diameter 8 cm, then find the height of the cone.
The ratio of the total surface area of a sphere and a hemisphere of same radius is
If the ratio of volumes of two spheres is 1 : 8, then the ratio of their surface areas 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
A cone and a hemisphere have equal bases and equal volumes the ratio of their heights is
Find the radius of the sphere whose surface area is equal to its volume .
The given figure shows the cross-section of a cone, a cylinder and a hemisphere all with the same diameter 10 cm and the other dimensions are as shown.
Calculate :
- the total surface area.
- the total volume of the solid and
- the density of the material if its total weight is 1.7 kg.
A spherical cannon ball, 28 cm in diameter is melted and recast into a right circular conical mould, the base of which is 35 cm in diameter. Find the height of the cone, correct to one place of decimal.
The radius of a sphere is 10 cm. If we increase the radius 5% then how many % will increase in volume?
The surface area of a solid metallic sphere is 616 cm2. It is melted and recast into smaller spheres of diameter 3.5 cm. How many such spheres can be obtained?
A solid sphere is cut into two identical hemispheres.
Statement 1: The total volume of two hemispheres is equal to the volume of the original sphere.
Statement 2: The total surface area of two hemispheres together is equal to the surface area of the original sphere.
Which of the following is valid?
