The formulae for calculating the areas of quadrilaterals, circles and triangles should already be known :- Area = 1 2 D x d CIRCLE.

Transcription

1 Revision - Areas Chapter 8 Volumes The formulae for calculating the areas of quadrilaterals, circles and triangles should already be known :- SQUARE RECTANGE RHOMBUS KITE B dd d D D Area = 2 Area = x B Area = 1 2 D x d Area = 1 2 D x d PARAEOGRAM TRIANGE CIRCE TRAPEZIUM b H H r h B B a Area = B x H Area = 1 2 B x H Area = πr 2 Area = 1 2 h(a + b) Exercise Use the appropriate formula from the above to calculate the areas of the following figures :- 2. Calculate the area of each figure by splitting it into shapes whose areas you can find easily :- 13 cm 1 4 cm 4 cm (d) (d) 11 cm 1 (e) (f) 8 m 11 mm (g) 20 m (h) 14 mm (e) (f) 14 cm 2 Chapter 8 this is page 77 Volumes

2 Revision - Volume and Surface Area The formulae for calculating the volume and surface area of a cube and cuboid should already be known. CUBE CUBOID CAPACITY H When you talk about the volume of a liquid quantity, you refer to it as its CAPACITY. B NOTE Volume = 3 Volume = x B x H 1 cm 3 = 1 millilitre (ml) S.A. = 6 x 2 S.A. = 2(B + H + BH) 1000 ml = 1 litre Exercise Calculate the volume of this cuboid in cubic cm, (cm 3 ). 5. This metal tank holds 67 2 litres when full. 2. The volume of this shallow block is cm How many millilitres is this? Calculate the height,, of the tank. 6. Calculate the volume of this tank in cm 3. Calculate its height (). 3. Calculate the volume of this box in cm cm m When the tap is opened fully, water flows in at the rate of 6 litres per minute. How long before the tank overflows? How many millilitres of liquid will it hold? What is its capacity in litres? 7. This tank is built to hold 1350 litres of oil. 4. How many litres of water will this box hold when it is only half full? 1 5 m 1 2 m 2 Calculate the height of the tank. Chapter 8 this is page 78 Volumes

3 8. Shown is a cube with each of its sides 1 metre, or 100 cm long. Calculate its volume in cubic metres (m 3 ). Now, calculate its 1 metre = 100 cm volume in cm 3. (100 x 100 x...). 13. This cuboid measures by by. Calculate its total surface area in cm 2. Hence, copy and complete the statement :- 1m 3 =... cm A cube measures 200 cm by 200 cm by 200 cm. Calculate its volume in cm 3. Now write down its volume in m Use the formula :- S.A. = 2(B + H + BH), to calculate the surface area of this cuboid. 10. Calculate the volume of this concrete block in both cubic centimetres and cubic metres. 300 cm 11. This podium is created using concrete. 80 cm cm Calculate the total volume in cm 3. How many cubic metres of concrete were used to make the podium? 12. ook at this cuboid. 90 cm cm 1 Calculate the area of its front face. By calculating the area of each of its other 5 faces, write down the total surface area of the cuboid. 15. This metal box is made from aluminium sheeting. The sheeting costs 3 2p per cm 2 to produce. Calculate the total surface area. Calculate the cost of the aluminium sheeting needed to make it. 16. An open topped metal container is to be manufactured to hold exactly 12 litres of oil. 2 Calculate the height of the metal box. Calculate the area of sheet metal which would be required to make the (open topped) container. 17. From a rectangular piece of card measuring by, four squares of side are removed from the corners. The remaining piece is then folded and glued to make the shallow tray shown. Calculate both the volume and the surface area of the tray. TRAY Chapter 8 this is page 79 Volumes

4 Prisms A PRISM is any solid shape with two parallel congruent faces (or ends) generally in the shape of polygons. Examples :- square based prism triangular prism hexagonal based prism pentagonal prism The RED face is the one that runs right through the shape, (top to bottom, left to right or front to back). Volume of a Prism It is very easy to calculate the volume of a prism, as long as you know the area of the congruent face. VOUME (prism) = Area (of end face) x length or VOUME (prism) = Area (of base) x height Area = 2 length = For this pentagonal prism, Volume = Area x length = 2 x * The usual formula is :- V = A x h = 2 3 Exercise The area of the top of this square based prism is 24 cm 2. Its height is. Calculate its volume. Area = 24 cm 2 4. The volume of this Area = 1 2 prism is 144 cm 3. Calculate the height of the prism. 2. Calculate the volume of this triangular prism. Area = Calculate the volume of this hexagonal based prism. Area = 80 cm 2 5 The volume of this prism Area = 2 6. The volume of this square based prism is 432 cm 3. Calculate the length of each side of its base. is Calculate the length of the prism. Chapter 8 this is page 80 Volumes

5 7. This is a (right angled) triangular prism. Calculate the area of the pink triangular face. Now calculate the volume of the prism. 8. Calculate the volume of this prism in a similar way. 9. The yellow face of this prism is an isosceles triangle. The base of the triangle is and its height is. Calculate the area of the yellow triangular face. Now calculate the volume of the prism. 10. The volume of this prism is 5 3. The isosceles triangle on top has base and height. Calculate the height of the prism. A Special Prism - the Cylinder r cm If the common face of a prism is a CIRCE, then the prism is called a CYINDER, and there is a special formula for calculating its volume. Volume = Area (of base) x height => V = πr 2 h Example :- Calculate the volume of this cylindrical tin can. 4 CYINDER V = πr 2 h V = 3 14 x 7 x 7 x 4 5 V = Exercise Calculate the volume of this cylinder with base radius and height. 2. Calculate the volume of this cylinder. 3. The diameter of the base of this cylinder is. Write down its radius. Calculate its volume These two cylindrical cans are to be filled with soup. Which one will hold more? A 5. This hot water tank has base diameter 60 cm. It is 80 cm tall. How many litres of water will it hold when full. (Find volume in ml first). B 60 cm 80 cm Chapter 8 this is page 81 Volumes

6 6. Backsters cook up their Cock-a-eekie soup in a large cylindrical pot. 11. This piece of gutter is 3 5 metres long. Calculate the volume of soup if the pot is full. Each tin holds 1 2 litre. How many tins can be filled from the pot? 7. A cylindrical bucket is used to fill a rectangular tank with hot water. 14 cm By calculating the volume of both the bucket and the tank, decide how many times the bucket will need to be used to fill the tank. 8. This section of pipe forms part of a sewer. If caps are fitted on the ends, how much water will the gutter hold when full? (in litres). 12. This toilet roll has a hollow cardboard tube in its middle. Calculate the volume of the actual toilet paper surrounding the tube. 13. This metal block has 4 identical cylindrical holes drilled out of it as shown. 3 5 m 4 cm The diameter of each circle is. 1 5 metres Calculate the volume of one of the holes. Calculate the volume of the metal block remaining after the holes have been drilled. How many litres of water will it hold? 9. This small gold ingot is cylindrical. Calculate its volume in cm 3. If 1 cm 3 of gold weighs 19 3 grams, calculate the weight of the ingot. 1 If gold is valued at per gram, determine the value of the gold ingot. 10. This trough is used to feed cattle with grain. 1 cm 14. George uses wooden beading as an edging round the skirting of his newly laid floor. The ends are quarter circles, with a radius of 1. Calculate the volume of a piece of beading which is 2 metres long. 1 2 metres 15. Timmy has a cube of plasticine of side 4 cm. 1 It is in the shape of a half-cylinder. Calculate the volume of grain it can hold. (Hint - find the volume of the whole cylinder). 4 cm He rolls it into a cylinder as shown with a base diameter of. Calculate the height (h) of the cylinder formed. Chapter 8 this is page 82 Volumes

7 Pyramids and the Cone A PYRAMID is any solid shape with a polygon as its base and triangular sides with a common vertex. Examples :- square based pyramid pentagonal based pyramid hexagonal based pyramid circular based pyramid Volume of a Pyramid It is possible to calculate the volume of a pyramid, as long as you know the area of the base. h = VOUME (pyramid) = 1 3 x Area (of base) x height Area = 80 cm 2 For this square based pyramid, Volume = = = 1 3 x Area x height 1 3 x 80 cm2 x 1 3 x 960 cm3 = 3 3 Exercise The area of the base of this square based pyramid is 13 cm 2. Its height is. Calculate its volume. Area = 13 cm 2 4. The base of this pyramid is a square with each side. It is tall. Calculate its volume. 2. Calculate the volume of this 7 triangular based pyramid. Area = 2 3. Calculate the volume of this hexagonal based pyramid. 7 2 cm Area = Shown are two cartons used to hold popcorn. 1 How much more does the big one hold than the small one? Chapter 8 this is page 83 Volumes

8 6. The base of this pyramid is an equilateral triangle with its sides long. Use Pythagoras Theorem to calculate the height () of the equilateral triangle. Now calculate the area of the triangular base and use this to find the volume of the pyramid. Special Case - The Cone A Circular Based Pyramid is simply called a CONE. The formula for its volume is :- V = 1 3 πr2 h 7. The radius of the base of this cone is and its height is. Copy and complete :- 8. Calculate the volumes of these cones :- Volume = 1 3 πr2 h => V = 3 14 x 5 x 5 x 9 3 => V =... cm 3 r cm 9. The volume of this cone is 400 cm 3. Calculate the area of its base. Now calculate the height () of the cone m A farmer uses this conical container to hold grain for his cattle. 4 8 m Calculate the weight of grain in the full container, if 1m 3 of grain weighs 750 kilograms. 11. This glass conical oil lamp has a base diameter of 24 cm and is 32 cm tall. How many litres of oil will the lamp hold when full? 12. This shape consists of a 1 conical tower on top of a cylindrical base. By calculating the volume of base and top, determine the volume of the whole shape. 13. This conical paper cup has a top diameter of and is 1 tall. It was filled with water and then some of the water was poured out. 24 cm 32 cm 6 5 m 1 4 cm (d) (diameter =) 1 3 m 8 2 mm 8 7 mm Calculate the volume of water in the paper cup when it was full. Calculate the volume of water poured out. Chapter 8 this is page 84 Volumes

9 Curved Surface Area of a Cylinder r cm The top of a cylinder is a circle and its area is easily found. ( A = πr 2 ). The curved bit is more difficult :- Imagine the label of a tin of soup cut and opened out to reveal - a rectangle. h The breadth of the rectangle this time is. πd The length is in fact the circumference of the top circle => = π D (can you see this?) => This means that the curved surface area is given by :- C.S.A. = π Dh => (nearly there!) - Since D = 2 x r, => C.S.A. = 2π rh is the formula used. Example :- Find the curved surface area of this cylinder :- C.S.A. = 2π rh => C.S.A. = 2 x 3 14 x 7 x 5 => C.S.A. = Exercise Calculate the C.S.A. of this cylinder with base radius and height. 5. Which of these two cylinders has the larger total surface area (T.S.A.)? 5 B A cm Calculate the C.S.A. of this cylinder. 6. This open topped can is made out of aluminium sheeting. 3. The diameter of the base of this cylinder is. Write down its radius. Calculate its C.S.A. 60 cm Calculate the area of aluminium sheeting needed to make it A paddling pool is made out of rigid plastic. 80 cm 3 4. This cylinder has top radius and height 1. 1 Calculate the area of the top surface. Calculate the C.S.A. of the cylinder. Now calculate the Total Surface Area of the cylinder. (top, bottom and curved bit). Calculate the total area of plastic required. 8. (Hard) This is the label off a tin of soup. 3 4 m Made from the finest vegetables grown in Scotland contents -... ml Brooster s eek Soup Calculate the volume of the tin of soup. Chapter 8 this is page 85 Volumes

10 Volume of a Sphere The correct name for a ball shape is a SPHERE. The volume* of a sphere is given by :- V = 4 3 πr 3 r cm SPHERE Example :- Calculate the volume of this football which has a diameter of. D = => r = V = 4 3 πr3 note V = 4 x 3 14 x 15 x 15 x 15 3 V = * It is not possible to prove this is the correct formula until you have met a mathematical topic called Integral Calculus. Exercise Calculate the volume of the sphere shown with radius. 5. This hot water tank consists of a hemi-sphere on top of a cylinder. The diameter of both the cylinder and hemisphere is 60 cm and the cylinder is tall. Calculate the total volume. 60 cm 2. Calculate the volume of this golf ball which has a diameter of 40 mm. 3. This box is tightly packed with 3 tennis balls. 6. This large metal shape is used to advertise Monty s 3 Ice-Cream Shop. 42 cm It consists of a hemi-sphere on top of a cone. Calculate the volume of the metal shape. Top Flight Tennis Balls - 3 Calculate the volume of 1 tennis ball. 7. A stainless steel ashtray is made by drilling out a hemi-sphere from a square based cuboid. The diameter of the hemi-sphere is. 4. The diameter of this hemispherical bowl is. Calculate its volume. How many litres of water would it hold when full? Calculate the volume of the ashtray. Calculate the weight of the ashtray given 1 cm 3 of stainless steel weighs 8 03 grams. Chapter 8 this is page 86 Volumes

11 Remember Remember...? Topic in a Nutshell 1. For the cuboid shown below, calculate its volume surface area. 7. Calculate the volume of this cone. 2. How many litres will this tank hold 80 cm when full? 1 2 m 8. This shape is formed from a cone and a cylinder. Calculate its volume Calculate the volume of each of these prisms :- Area = Calculate the volume of this tank in cm 3 and write down its capacity in litres When this pipe is filled with oil, it holds 5 litres. 9. For the metal cylinder shown below, calculate :- the area of the top the curved surface area the total surface area. 14 cm 10. This statue is used to advertise Townend 3 2 m Bowling Club. Calculate the volume of the sphere used in the sign.? cm 11. Calculate the capacity (in litres), of this bowl. 4 How many millilitres is this? Calculate what the pipe length must be. 6. Calculate the volume of each of these pyramids cm 12. This shape consists 13 cm of a cone on top of a cylinder on top of a hemi-sphere. Calculate the total volume of the shape. Area = 80 cm 2 24 cm Chapter 8 this is page 87 Volumes