Edexcel M1 — Question 2 7 marks

Exam BoardEdexcel
ModuleM1 (Mechanics 1)
Marks7
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicForces, equilibrium and resultants
TypeEquilibrium with friction on horizontal surface
DifficultyStandard +0.8 This is a challenging M1 statics problem requiring resolution of forces in two perpendicular directions, application of friction law (F = μR), and solving simultaneous equations with multiple unknowns. The 'point of moving' condition and non-standard angles (45° and 30°) make it significantly harder than routine equilibrium problems, but it's still within standard M1 scope.
Spec3.03e Resolve forces: two dimensions3.03r Friction: concept and vector form3.03s Contact force components: normal and frictional3.03t Coefficient of friction: F <= mu*R model3.03u Static equilibrium: on rough surfaces

\includegraphics{figure_2} A small packet of mass 0.3 kg rests on a rough horizontal surface. The coefficient of friction between the packet and the surface is \(\frac{1}{4}\). Two strings are attached to the packet, making angles of 45° and 30° with the horizontal, and when forces of magnitude 2 N and \(F\) N are exerted through the strings as shown, the packet is on the point of moving in the direction \(\overrightarrow{AB}\). Find the value of \(F\). \hfill [7 marks]

AnswerMarks Guidance
Resolve horizontally: \(F \cos 30° = 2 \cos 45° + 0.25R\)M1 A1
Resolve vertically: \(R + 2 \sin 45° + F \sin 30° = 0.3g\)M1 A1
\(0.866F = 1.414 + 0.25(0.3g - 1.414 - 0.5F)\)M1 A1
\(0.991F = 1.796\) → \(F = 1.81\)A1 Total: 7 marks
Resolve horizontally: $F \cos 30° = 2 \cos 45° + 0.25R$ | M1 A1 |

Resolve vertically: $R + 2 \sin 45° + F \sin 30° = 0.3g$ | M1 A1 |

$0.866F = 1.414 + 0.25(0.3g - 1.414 - 0.5F)$ | M1 A1 |

$0.991F = 1.796$ → $F = 1.81$ | A1 | **Total: 7 marks**
\includegraphics{figure_2}

A small packet of mass 0.3 kg rests on a rough horizontal surface. The coefficient of friction between the packet and the surface is $\frac{1}{4}$. Two strings are attached to the packet, making angles of 45° and 30° with the horizontal, and when forces of magnitude 2 N and $F$ N are exerted through the strings as shown, the packet is on the point of moving in the direction $\overrightarrow{AB}$.

Find the value of $F$. \hfill [7 marks]

\hfill \mbox{\textit{Edexcel M1  Q2 [7]}}