Resultant of two forces (triangle/parallelogram law)

Given two forces with magnitudes and angle between them, find the magnitude and/or direction of the resultant using the cosine or sine rule (triangle of forces).

7 questions · Moderate -0.7

3.03p Resultant forces: using vectors
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CAIE M1 2002 June Q3
5 marks Moderate -0.3
3 \includegraphics[max width=\textwidth, alt={}, center]{430f1f9a-7a3a-47a0-b742-daf74e68adfd-2_368_584_1302_794} Two forces, each of magnitude 10 N , act at a point \(O\) in the directions of \(O A\) and \(O B\), as shown in the diagram. The angle between the forces is \(\theta\). The resultant of these two forces has magnitude 12 N .
  1. Find \(\theta\).
  2. Find the component of the resultant force in the direction of \(O A\).
CAIE M1 2012 June Q2
5 marks Standard +0.3
2 \includegraphics[max width=\textwidth, alt={}, center]{01e73486-5a95-4e65-bf18-518d1adc7cfb-2_318_632_482_753} Forces of magnitudes 13 N and 14 N act at a point \(O\) in the directions shown in the diagram. The resultant of these forces has magnitude 15 N . Find
  1. the value of \(\theta\),
  2. the component of the resultant in the direction of the force of magnitude 14 N .
Edexcel M1 2001 June Q2
8 marks Moderate -0.8
2. \begin{figure}[h]
\captionsetup{labelformat=empty} \caption{Figure 1} \includegraphics[alt={},max width=\textwidth]{218383c1-0875-46f2-9416-8e827065a7a6-2_272_592_1239_648}
\end{figure} Two forces \(\mathbf { P }\) and \(\mathbf { Q }\), act on a particle. The force \(\mathbf { P }\) has magnitude 5 N and the force \(\mathbf { Q }\) has magnitude 3 N . The angle between the directions of \(\mathbf { P }\) and \(\mathbf { Q }\) is \(40 ^ { \circ }\), as shown in Fig. 1. The resultant of \(\mathbf { P }\) and \(\mathbf { Q }\) is \(\mathbf { F }\).
  1. Find, to 3 significant figures, the magnitude of \(\mathbf { F }\).
  2. Find, in degrees to 1 decimal place, the angle between the directions of \(\mathbf { F }\) and \(\mathbf { P }\).
Edexcel M1 2017 January Q3
8 marks Moderate -0.8
3. \begin{figure}[h]
\includegraphics[alt={},max width=\textwidth]{ba698f74-a51c-409a-a9d9-e9080fc87be2-05_520_730_264_607} \captionsetup{labelformat=empty} \caption{Figure 1}
\end{figure} Two forces \(\mathbf { P }\) and \(\mathbf { Q }\) act on a particle at a point \(O\). Force \(\mathbf { P }\) has magnitude 6 N and force \(\mathbf { Q }\) has magnitude 7 N . The angle between the line of action of \(\mathbf { P }\) and the line of action of \(\mathbf { Q }\) is \(120 ^ { \circ }\), as shown in Figure 1. The resultant of \(\mathbf { P }\) and \(\mathbf { Q }\) is \(\mathbf { R }\). Find
  1. the magnitude of \(\mathbf { R }\),
  2. the angle between the line of action of \(\mathbf { R }\) and the line of action of \(\mathbf { P }\).
Edexcel M1 2017 June Q7
8 marks Moderate -0.8
7. \begin{figure}[h]
\includegraphics[alt={},max width=\textwidth]{5c3869c7-008f-4131-b68d-8ecdd4da3377-22_254_291_251_831} \captionsetup{labelformat=empty} \caption{Figure 3}
\end{figure} Two forces, \(\mathbf { P }\) and \(\mathbf { Q }\), act on a particle. The force \(\mathbf { P }\) has magnitude 8 N and the force \(\mathbf { Q }\) has magnitude 5 N . The angle between the directions of \(\mathbf { P }\) and \(\mathbf { Q }\) is \(50 ^ { \circ }\), as shown in Figure 3. The resultant of \(\mathbf { P }\) and \(\mathbf { Q }\) is the force \(\mathbf { R }\).
  1. Find, to 3 significant figures, the magnitude of \(\mathbf { R }\).
  2. Find, to the nearest degree, the size of the angle between the direction of \(\mathbf { P }\) and the direction of \(\mathbf { R }\).
OCR M1 2010 January Q2
8 marks Moderate -0.8
2 Two horizontal forces of magnitudes 12 N and 19 N act at a point. Given that the angle between the two forces is \(60 ^ { \circ }\), calculate
  1. the magnitude of the resultant force,
  2. the angle between the resultant and the 12 N force.
AQA AS Paper 1 2024 June Q14
1 marks Easy -1.8
Two forces, \(\mathbf{F}_1 = 3\mathbf{i} + 2\mathbf{j}\) newtons and \(\mathbf{F}_2 = \mathbf{i} - 3\mathbf{j}\) newtons, are added together to find a resultant force, \(\mathbf{R}\) newtons. This vector addition can be represented using a diagram. Identify the diagram below which correctly represents this vector addition. Tick (\(\checkmark\)) one box. [1 mark] \includegraphics{figure_14}