Cylinder

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
  Because it has a curved surface it is not a polyhedron.
   
And for reference:
  Surface Area = 2 × π × r × (r+h)
 
  • Surface Area of One End = π × r2
  • Surface Area of Side = 2 × π × r × h
  Volume = π × r2 × h
Cylinder Dimensions Instructions: In "spin" mode it freely spins and will respond to your mouse. In "drag" mode it stops spinning and you can use your mouse to move it.



An object shaped like a cylinder is said to be cylindrical

Volume of a Cylinder

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

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

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!)

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.

More Cylinders