The curved surface area of a cylinder is $3960\, cm^{2}$. If its radius is $21\, cm$,find its height in $cm$.

Find the curved surface area and the total surface area of a hemisphere with a radius of $14\, cm$.

The surface area of a sphere with a radius of $5 \, cm$ is five times the curved surface area of a cone with a radius of $4 \, cm$. Find the height and volume of the cone (take $\pi = \frac{22}{7}$).

$A$ cylindrical tube open at both ends is made of an iron sheet which is $2 \, cm$ thick. If the outer diameter is $16 \, cm$ and its length is $100 \, cm$, find how many cubic centimeters of iron have been used in making the tube? (in $cm^3$)

Find the volume of a sphere of radius $2.1 \, cm$. (in $cm^3$)

Find the surface area of a sphere of radius $1.25 \, m$ $(\pi = 3.14)$ (in $m^2$).