1. Revision Volume of a Cone V = 1/3 x 3.14 x (5)2 x 12 V = 1/3 x 942 V = 314 Find the Volume of this Cone taking π as 3.14

2. Calculate the volume of the cylinder: 5cm 6cm Volume of cylinder = r² h Volume = x (2.5)² x 6 = 37.5 = 117.8 cm³ (to 1 dp)

3. Spheres Aim: to calculate the volume of a sphere

4. Real Life Spheres mm

6. Sand Activity • Find the volume of the sphere using the sand and your knowledge of the Cylinder.

7. r V1 If we make a cone having radius and height equal to the radius of sphere. Then a water filled cone can fill the sphere in 4 times. r r V=1/3 πr2h If h = r then V=1/3 πr3 V1 = 4V = 4(1/3 πr3) = 4/3 πr3

8. Volume of a Sphere Click to See the experiment r r h=r Here the vertical height and radius of cone are same as radius of sphere. 4( volume of cone) = volume of Sphere 4( 1/3πr2h) = 4( 1/3πr3 ) = V V = 4/3 π r3

9. Volume of a sphere r Radius of a sphere YouTube

10. Volume of a Sphere 10 cm

11. Find the volume of the following sphere. Vs = (4/3)r3 = (4/3)(15)3 = (4/3)(3375) = 4500 = 14137m3 30m

12. Now its your turn!

13. TPS The diameter of the ball is 21cm, so the radius is = 10.5cm. 21 2 4 4 V = πr3 V = x 3.14 x (10.5)3 3 3 The Gaelic Football ball has a diameter of 21 cm. Find its volume. SOLUTION Answer

14. The Basketball has a radius of 13cm. Find its volume.

15. A Tennis ball has a diameter of 6.5 cm. • Find its Volume.