A cylinder is a circular prism. As with other prisms, the volume of a cylinder can be calculated using the cross-sectional area x length.
Th cross-section of a cylinder is a circle. As the area of a circle =`πr^2`, the volume of a cylinder is `πr^2l`, where `r` is the radius of the circular end, and `l` is the length of the cylinder.
What is the volume of a cylinder with a diameter of 4cm and a length of 42cm? Give your answer correct to 1 decimal place.
|For a circle:||Area||`= pir^2`|
|Substitute||`A`||`= pi xx 2^2`|
The cross-sectional area is `4pi`
|For a cylinder:||Volume||= area xx length|
|Substitute||V||`= 4pi xx 42`|
Answer: 527.8 cm3
What is the diameter of a cylinder with a volume of 1000cm3 and a length of 100cm? Give the answer correct to 1 decimal place.
|For a Cylinder||Volume||`= pir^2l`|
|Substitute||`1000`||`= pir^2 xx 100`|
|Divide both sides by 100||10||`= pir^2`|
|Divide both sides by `pi`||3.183||`= r^2`|
|Square root||1.784||`= r`|