Cylinder

Go to Surface Area or Volume.

Cylinder Facts

Notice these interesting things:

  • It has a flat base and a
    flat top
  • The base is the same as
    the top, and also in-between
  • It has one curved side
  • It is not a polyhedron as it
    has a curved surface

An object shaped like a cylinder is said to be cylindrical.

 

 

Cylinder Dimensions

Surface Area of a Cylinder

Surface Area = 2 × π × r × (r+h)

Which is made up of:

  • Surface Area of One End = π × r2
  • Surface Area of Side = 2 × π × r × h

Example: h = 7 and r = 2

Surface Area   = 2 × π × r × (r+h)
    = 2 × π × 2 × (2+7)
    = 2 × π × 2 × 9
    = 36 π
    113.097

Volume of a Cylinder

Volume = π × r2 × h

Just multiply the area of the base by the height of the cylinder:

  • Area of the base: π × r2
  • Height: h
  • Volume = Area × Height = π × r2 × h

Example: h = 7 and r = 2

Volume   = π × r2 × h
    = π × 22 × 7
    = 28 π
      87.96

How to remember: Volume = pizza

Cylinder Pizza

Imagine you just cooked a pizza.

The radius is "z", and the thickness "a" is the same everywhere ... what is the volume?

Answer: pi × z × z × a

(we would normally write "pi" as π, and z × z as z2, but you get the idea!)

Volume of a Cone vs Cylinder

The volume formulas for cylinders and cones are very similar:

The volume of a cylinder is:   π × r2 × h
The volume of a cone is:   1 3 π × r2 × h

So a cone's volume is exactly one third ( 1 3 ) of a cylinder's volume.

In future, order your ice creams in cylinders, not cones, you get 3 times as much!

It Doesn't Have to Be Circular

Usually when we say Cylinder we mean a Circular Cylinder, but you can also have Elliptical Cylinders, like this one:

You can even have stranger cylinders: if the cross-section is curved and is the same from one end to the other, then it will still be a cylinder.

But the area and volume calculations will be different than above.

More Cylinders

 

 
Search :: Index :: About :: Contact :: Contribute :: Cite This Page :: Privacy

Copyright © 2015 MathsIsFun.com