Mathematics 9709 · AS & A Level · Representation of data

Representation of data — practice question

A uniform solid cone of height $0.8\,\text{m}$ and semi-vertical angle $30^\circ$ weighs $20\,\text{N}$. It is in equilibrium with one point $P$ on its base touching a rough horizontal plane, while the vertex $V$ is directly above $P$. A force of magnitude $F\,\text{N}$, acting along the cone’s axis of symmetry and applied at $V$, keeps it balanced (see diagram).
(i)[2]

Demonstrate that the moment of the cone’s weight about $P$ equals $6\,\text{N m}$.

(ii)[2]

So find $F$.

Worked solution & mark scheme

This 4-mark question has a full step-by-step worked solution and mark scheme. One marking point: Horizontal distance can be written as $0.8\times\dfrac{3}{4}\times\sin 30$ or an equivalent moment set-up

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