CAIE M1 2020 June — Question 1 3 marks

Exam BoardCAIE
ModuleM1 (Mechanics 1)
Year2020
SessionJune
Marks3
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicForces, equilibrium and resultants
TypeResultant of coplanar forces
DifficultyModerate -0.8 This is a straightforward vector resolution problem requiring students to resolve three forces into components and find the resultant magnitude and direction. The given value of cos α simplifies calculations (avoiding messy trigonometry), and the method is a standard textbook exercise in M1. It's easier than average A-level questions as it's purely procedural with no problem-solving insight required, though not trivial since it involves multiple force components.
Spec3.03p Resultant forces: using vectors

Three coplanar forces of magnitudes \(100\text{ N}\), \(50\text{ N}\) and \(50\text{ N}\) act at a point \(A\), as shown in the diagram. The value of \(\cos \alpha\) is \(\frac{4}{5}\). \includegraphics{figure_1} Find the magnitude of the resultant of the three forces and state its direction. [3]

Question 1:
AnswerMarks Guidance
1Resultant = 100 – 2 × 50cos α M1
20 NA1
Direction is to the left (or equivalent)B1
3
AnswerMarks Guidance
QuestionAnswer Marks
Question 1:
1 | Resultant = 100 – 2 × 50cos α | M1
20 N | A1
Direction is to the left (or equivalent) | B1
3
Question | Answer | Marks
Three coplanar forces of magnitudes $100\text{ N}$, $50\text{ N}$ and $50\text{ N}$ act at a point $A$, as shown in the diagram. The value of $\cos \alpha$ is $\frac{4}{5}$.

\includegraphics{figure_1}

Find the magnitude of the resultant of the three forces and state its direction. [3]

\hfill \mbox{\textit{CAIE M1 2020 Q1 [3]}}