Advertisements
Advertisements
Question
Find the radius of a sphere whose surface area is equal to the area of the circle of diameter 2.8 cm
Advertisements
Solution
Diameter of circle = 2.8 cm ⇒ radius = r = 1.4 cm
Area of a circle = `pir^2`
= `pi(1.4)^2`
= `1.96pi`
Surface area of sphere = `4pir^2`
Given ,
Surface area of sphere = Area of the circle
⇒ `4pir^2 = 1.96pi`
⇒ `r^2 = 1.96/4`
⇒ `r^2 = 0.49`
⇒ `r = 0.7 "cm"`
Radius of the sphere = 0. 7 cm
APPEARS IN
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]`
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 spherical ball of lead has been melted and made into identical smaller balls with radius equal to half the radius of the original one. How many such balls can be made?
If the number of square centimeters on the surface of a sphere is equal to the number of cubic centimeters in its volume, what is the diameter of the sphere?
A hemi-spherical bowl has negligible thickness and the length of its circumference is 198 cm. Find the capacity of the bowl.
The diameter of a sphere is 6 cm. It is melted and drawn into a wire of diameter 0.2 cm. Find the length of the wire.
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
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
Find the length of the wire of diameter 4 m that can be drawn from a solid sphere of radius 9 m.
