Question

In the diagrams below four cones are depicted, such with a height of 12 cm. The position of the centre of gravity is indicated by dots located at 9 cm, 8 cm, 4 cm and 3 cm from the apex of each cone. Which of these cones is completely solid?

Options

• 9 cm

• 8 cm

• 4 cm

• 3 cm

Answer 1

9 cm

Explanation:

For a completely solid cone, the centre of gravity is at one-quarter of its height from the base. So its distance from the apex is $$\frac{3}{4} \times 12\text{ cm} = 9\text{ cm}$$. The other distances do not give this position.