AQA Paper 2 2018 June — Question 13 8 marks

Exam BoardAQA
ModulePaper 2 (Paper 2)
Year2018
SessionJune
Marks8
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicFriction
TypeSingle angled force - find limiting friction or coefficient
DifficultyModerate -0.3 This is a standard A-level mechanics friction problem requiring resolution of forces and comparison with limiting friction. Part (a) is straightforward calculation (F < μR), while part (b) adds angle resolution but follows the same method. The 8 marks reflect routine application of well-practiced techniques with no novel problem-solving required, making it slightly easier than average.
Spec3.03r Friction: concept and vector form3.03t Coefficient of friction: F <= mu*R model3.03u Static equilibrium: on rough surfaces
In this question use \(g = 9.8\) m s\(^{-2}\) A boy attempts to move a wooden crate of mass 20 kg along horizontal ground. The coefficient of friction between the crate and the ground is 0.85
  1. The boy applies a horizontal force of 150 N. Show that the crate remains stationary. [3 marks]
  2. Instead, the boy uses a handle to pull the crate forward. He exerts a force of 150 N, at an angle of 15° above the horizontal, as shown in the diagram. \includegraphics{figure_5} Determine whether the crate remains stationary. Fully justify your answer. [5 marks]
Question 13:
AnswerMarks Guidance
13(a)Uses model for
maximum friction mgAO3.3 B1
max
0.85209.8
166.6N
150 < 166.6
∴ crate does not move
AnswerMarks Guidance
Makes an appropriate comparisonAO1.1a M1
Explains clearly why crate remains
AnswerMarks Guidance
stationaryAO2.4 E1
AnswerMarks
13(b)Forms an equation by resolving
vertically
Condone one of sign error or cos
AnswerMarks Guidance
errorAO3.1b M1
R 157.177N
F 157.177
max
133.6N
150cos15145N
145 > 133.6
∴ crate begins to move
AnswerMarks Guidance
Obtains correct reaction forceAO1.1b A1
Uses maximum friction R
With ‘their’ reaction force
Must identify maximum or limiting
AnswerMarks Guidance
frictionAO1.1b B1F
Compares 150cos15with ‘their’
AnswerMarks Guidance
maximum frictionAO1.1a M1
Explains, using their values, why
AnswerMarks Guidance
the crate begins to move.AO2.4 E1F
Total8
QMarking Instructions AO 
Question 13:
--- 13(a) ---
13(a) | Uses model for
maximum friction mg | AO3.3 | B1 | F mg
max
0.85209.8
166.6N
150 < 166.6
∴ crate does not move
Makes an appropriate comparison | AO1.1a | M1
Explains clearly why crate remains
stationary | AO2.4 | E1
--- 13(b) ---
13(b) | Forms an equation by resolving
vertically
Condone one of sign error or cos
error | AO3.1b | M1 | 20g  R150sin15
R 157.177N
F 157.177
max
133.6N
150cos15145N
145 > 133.6
∴ crate begins to move
Obtains correct reaction force | AO1.1b | A1
Uses maximum friction R
With ‘their’ reaction force
Must identify maximum or limiting
friction | AO1.1b | B1F
Compares 150cos15with ‘their’
maximum friction | AO1.1a | M1
Explains, using their values, why
the crate begins to move. | AO2.4 | E1F
Total | 8
Q | Marking Instructions | AO | Marks | Typical Solution
In this question use $g = 9.8$ m s$^{-2}$

A boy attempts to move a wooden crate of mass 20 kg along horizontal ground. The coefficient of friction between the crate and the ground is 0.85

\begin{enumerate}[label=(\alph*)]
\item The boy applies a horizontal force of 150 N. Show that the crate remains stationary.
[3 marks]

\item Instead, the boy uses a handle to pull the crate forward. He exerts a force of 150 N, at an angle of 15° above the horizontal, as shown in the diagram.

\includegraphics{figure_5}

Determine whether the crate remains stationary.

Fully justify your answer.
[5 marks]
\end{enumerate}

\hfill \mbox{\textit{AQA Paper 2 2018 Q13 [8]}}
This paper (17 questions)
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Q1 1 Q2 1 Q3 1 Q4 6 Q5 2 Q6 7 Q7 8 Q8 10 Q9 14 Q10 1 Q11 1 Q12 5 Q13 8 Q14 6 Q15 9 Q16 6 Q17 14