MATHEMATICSVolume of prisms and cylinders

Lesson Objectives

•The aim of this powerpoint is to help you…

• to learn and use the formula for finding the volume of a prism

• to learn and use the formula for finding the volume of a cylinder

Dimensions

REMEMBER:

• ADDING distances, areas or volumes together makes longer distances, bigger areas or bigger volumes

• You have to MULTIPLY dimensions or distances together to get areas or volumes

• As area is already 2D, you can find a volume by multiplying an area by another perpendicular dimension

Volume of Prisms• The volume of a prism is the area of its cross section (i.e. the shape

that goes through the whole shape and gives the prism its name) multiplied by its height (or length)

• V = Ah

• To find the area of the cross section you will need to recall how to find the area of rectangles, triangles and rectilinear shapes.

Area

Area

length

height

Volume of Cylinders

• A cylinder is a special type of prism – a circular prism.

• You use the same formula but ‘A’ (the area) can be replaced by the formula for the area of a circle.

• V = Ah V = πr²h

radius

radius

length

height

V V

A h πr² h

Quick Practice

Find the volume of this prism and cylinder…

20cm²6cm 9m

3m

Solutions…

Volume = area of cross section × height

Volume = 20cm² × 6cm = 120cm³

20cm²6cm 9m

3m

Volume = (3.14 × 3m × 3m) × 9m = 254.34m³

What next?• Print out the notes called PAV5b-VolumeP. Read through them and make

sure you answer any questions.

• Work through the MyMaths lesson and its online homework called Volume of Prisms found at:

• http://app.mymaths.co.uk/336-resource/volume-of-prisms• http://app.mymaths.co.uk/336-homework/volume-of-prisms

• Now work through the MyMaths lesson and its online homework called Volume of Cylinders found at:

• http://app.mymaths.co.uk/337-resource/volume-of-cylinders• http://app.mymaths.co.uk/337-homework/volume-of-cylinders

• Save and complete the worksheet called VolP-S1.xlsx

• Now prepare a revision sheet for your Geometry 2 assessment.