(a)
For the correct answer:
cone
For the explanation:
(because it has) lower centre of mass/gravity
The stability of an object is determined by the position of its centre of gravity. A cone has a wider base and its mass is distributed lower down compared to a cylinder of the same material and height, resulting in a lower centre of gravity. An object with a lower centre of gravity requires a greater angle of tilt before its line of action of weight falls outside its base, making it more stable.
(b)
For the correct answer:
(weight =) 2.5 (N)
Weight is the gravitational force acting on an object’s mass and is calculated using the equation $W = mg$, where $g$ is the gravitational field strength ($9.8\text{ m/s}^2$ or approximately $10\text{ m/s}^2$ on Earth). Substituting the given mass: $W = 0.25\text{ kg} \times 10\text{ N/kg}$ (or $9.8\text{ N/kg}$) $= 2.5\text{ N}$ (or $2.45\text{ N}$).
(c)(i)
For the correct answer:
(moment =) 66 (Ncm)
The moment of a force is the measure of its turning effect and is calculated by multiplying the force by the perpendicular distance from the pivot. In Fig. 3.2, the horizontal force of $3.0\text{ N}$ acts at a perpendicular distance of $22\text{ cm}$ from the pivot. Therefore, the moment $= 3.0\text{ N} \times 22\text{ cm} = 66\text{ Ncm}$.
(c)(ii)
For the correct answer:
(moment of weight =) answer to (c)(i) OR 66 (Ncm)
According to the principle of moments, for an object in equilibrium (as the cone is balancing on one edge), the sum of the clockwise moments about the pivot must equal the sum of the anticlockwise moments. The $3.0\text{ N}$ force creates a clockwise moment. The weight of the cone, acting downwards through its centre of gravity, creates an equal and opposite anticlockwise moment to maintain the balance.
