Sec 1 · G1 (N(T))

Volume and surface area

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1. Cubes, cuboids and prisms

Solid	Volume	Total surface area
cube, side $l$	$l^{3}$	$6l^{2}$
cuboid	$l \times b \times h$	$2(lb + lh + bh)$
prism	area of cross-section $\times$ length	$2 \times$ area of cross-section $+$ perimeter of cross-section $\times$ length
cylinder	$\pi r^{2}h$	$2\pi r^{2} + 2\pi rh$

Cuboid 8 cm by 3 cm by 5 cm

\displaystyle V = 8 \times 3 \times 5

e.g.

\displaystyle 8 \times 3 \times 5

\displaystyle = 120

$120\text{ cm}^{3}$
surface area: $2(8 \times 3 + 8 \times 5 + 3 \times 5)$ , which is $158\text{ cm}^{2}$

Triangular prism: cross-section a right triangle 3 cm by 4 cm, length 7 cm

\displaystyle V = \dfrac{1}{2} \times 3 \times 4 \times 7

e.g.

\displaystyle \dfrac{1}{2} \times 3 \times 4 \times 7

\displaystyle = 42

$42\text{ cm}^{3}$

📖 Worked example

The diagram shows a tent in the shape of a triangular prism. Find its volume.

Step 1 of 2

Area of the triangle (the cross-section)

\text{Area} = \dfrac{1}{2} \times 6 \times 4

= 12

cm²

📖 Worked example

The diagram shows a wooden chest in the shape of a cuboid. Find its total surface area.

Step 1 of 1

Six faces in three equal pairs: top and bottom, front and back, the two ends

\text{TSA} = 2(9 \times 4) + 2(9 \times 7) + 2(4 \times 7)

= 254

cm²

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2. Cylinders

Volume, radius 5 cm and height 12 cm

\displaystyle V = \pi r^{2}h

e.g.

\displaystyle \pi(5)^{2}(12)

\displaystyle = 300\pi

\displaystyle = 942\text{ (3 s.f.)}

Curved surface only: no circles

\displaystyle 2\pi rh

e.g.

\displaystyle 2\pi(5)(12)

\displaystyle = 120\pi

\displaystyle = 377\text{ (3 s.f.)}

📖 Worked example

The diagram shows a cylindrical candle. Find its volume, correct to 3 significant figures.

Step 1 of 1

Volume of a cylinder = πr²h: round at the end

V = \pi r^2 h

= \pi(3)^2(4)

= 113.0973\ldots

= 113

cm³ (3 s.f.)

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3. Units of volume

Volume	Equals
$1\text{ m}^{3}$	$1\,000\,000\text{ cm}^{3}$
$1\text{ litre}$	$1000\text{ cm}^{3}$
$1\text{ m}^{3}$	$1000\text{ litres}$
$1\text{ ml}$	$1\text{ cm}^{3}$

📖 Worked example

A cuboid container measures $120$ cm by $50$ cm by $40$ cm. Find its capacity, in litres.

Step 1 of 2

Volume of the tank in cm³

V = 120 \times 50 \times 40

= 240\,000

cm³

Practise this →

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1. Cubes, cuboids and prisms

Solid	Volume	Total surface area
cube, side $l$	$l^{3}$	$6l^{2}$
cuboid	$l \times b \times h$	$2(lb + lh + bh)$
prism	area of cross-section $\times$ length	$2 \times$ area of cross-section $+$ perimeter of cross-section $\times$ length
cylinder	$\pi r^{2}h$	$2\pi r^{2} + 2\pi rh$

Cuboid 8 cm by 3 cm by 5 cm

\displaystyle V = 8 \times 3 \times 5

e.g.

\displaystyle 8 \times 3 \times 5

\displaystyle = 120

$120\text{ cm}^{3}$
surface area: $2(8 \times 3 + 8 \times 5 + 3 \times 5)$ , which is $158\text{ cm}^{2}$

Triangular prism: cross-section a right triangle 3 cm by 4 cm, length 7 cm

\displaystyle V = \dfrac{1}{2} \times 3 \times 4 \times 7

e.g.

\displaystyle \dfrac{1}{2} \times 3 \times 4 \times 7

\displaystyle = 42

$42\text{ cm}^{3}$

📖 Worked example

The diagram shows a tent in the shape of a triangular prism. Find its volume.

Step 1 of 2

Area of the triangle (the cross-section)

\text{Area} = \dfrac{1}{2} \times 6 \times 4

= 12

cm²

📖 Worked example

The diagram shows a wooden chest in the shape of a cuboid. Find its total surface area.

Step 1 of 1

Six faces in three equal pairs: top and bottom, front and back, the two ends

\text{TSA} = 2(9 \times 4) + 2(9 \times 7) + 2(4 \times 7)

= 254

cm²

Practise this →

2. Cylinders

Volume, radius 5 cm and height 12 cm

\displaystyle V = \pi r^{2}h

e.g.

\displaystyle \pi(5)^{2}(12)

\displaystyle = 300\pi

\displaystyle = 942\text{ (3 s.f.)}

Curved surface only: no circles

\displaystyle 2\pi rh

e.g.

\displaystyle 2\pi(5)(12)

\displaystyle = 120\pi

\displaystyle = 377\text{ (3 s.f.)}

📖 Worked example

The diagram shows a cylindrical candle. Find its volume, correct to 3 significant figures.

Step 1 of 1

Volume of a cylinder = πr²h: round at the end

V = \pi r^2 h

= \pi(3)^2(4)

= 113.0973\ldots

= 113

cm³ (3 s.f.)

Practise this →

3. Units of volume

Volume	Equals
$1\text{ m}^{3}$	$1\,000\,000\text{ cm}^{3}$
$1\text{ litre}$	$1000\text{ cm}^{3}$
$1\text{ m}^{3}$	$1000\text{ litres}$
$1\text{ ml}$	$1\text{ cm}^{3}$

📖 Worked example

A cuboid container measures $120$ cm by $50$ cm by $40$ cm. Find its capacity, in litres.

Step 1 of 2

Volume of the tank in cm³

V = 120 \times 50 \times 40

= 240\,000

cm³

Practise this →