Mathematics 9709 · AS & A Level · Probability

Probability — practice question

Rod $AB$, with non-uniform density, has length $0.6\text{ m}$ and weight $9\text{ N}$. Its centre of mass lies $0.4\text{ m}$ from $A$. End $A$ of the rod is touching a rough vertical wall. The rod is in equilibrium, perpendicular to the wall, because a light string is fixed to $B$. The string is at an angle of $30^\circ$ to the horizontal. The tension in the string is $T\text{ N}$ (see diagram).
(i)[2]

Calculate the value of $T$.

(ii)[3]

Determine the least possible value of the coefficient of friction at $A$.

Worked solution & mark scheme

This 5-mark question has a full step-by-step worked solution and mark scheme. One marking point: Takes moments about $A$: $9 \times 0.4 = 0.6 \times T \sin 30$

  • Full mark scheme, point by point
  • Step-by-step worked solution
  • Write your answer & get it marked instantly by AI