CAIE M2 2013 November — Question 6 8 marks

Exam BoardCAIE
ModuleM2 (Mechanics 2)
Year2013
SessionNovember
Marks8
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicMomentum and Collisions 1
TypeRange of coefficient of restitution
DifficultyModerate -0.3 This is a standard two-part collision problem requiring application of conservation of momentum and Newton's law of restitution. Part (i) involves routine algebraic manipulation of two simultaneous equations to find velocities in terms of u and e. Part (ii) requires setting up and solving a simple inequality. While it involves multiple steps, the techniques are entirely standard for M2 collision problems with no novel insight required, making it slightly easier than average.
Spec6.03b Conservation of momentum: 1D two particles6.03k Newton's experimental law: direct impact

Two particles \(A\) and \(B\) have masses \(3m\) and \(2m\) respectively. Initially \(A\) is at rest and \(B\) is moving with speed \(u\) in a straight line towards \(A\). The coefficient of restitution between the particles is \(e\).
  1. Find the speeds of the particles immediately after the collision.
  2. Find the condition on \(e\) for \(A\) to be moving faster than \(B\) after the collision.
[8]

Question 6:

AnswerMarks
6 (i)0.4 g = 50e/0.8
Moves down = 0.044 m
0.4 × 1.5 2 /2 + 0.4 g × 0.044 +
50(0.82–0.8) 2 /(2 × 0.8)
=0.4v2 /2 + 50 × 0.064 2 /(2 × 0.8)
AnswerMarks
v = 1.6(0) ms −1M1
A1
M1
A1
AnswerMarks Guidance
A1[5] Uses T = λ × /L (e = 0.064)
(0.8 + 0.064 – 0.82)
Sets up 2EE/2KE/PE equation
AnswerMarks
(ii)PE gain to reach O = 0.4 g × 0.82
KE + EE = 0.4 × 1.5 2 /2
+50(0.82 – 0.8) 2 /(2 × 0.8)
Shows by evaluation that insufficient
AnswerMarks
energyB1
M1
AnswerMarks Guidance
A1[3] From initial position, (3.28J)
At initial position, (0.4625J)8
Page 6Mark Scheme Syllabus
GCE A LEVEL – October/November 20139709 53
Question 6:
--- 6 (i) ---
6 (i) | 0.4 g = 50e/0.8
Moves down = 0.044 m
0.4 × 1.5 2 /2 + 0.4 g × 0.044 +
50(0.82–0.8) 2 /(2 × 0.8)
=0.4v2 /2 + 50 × 0.064 2 /(2 × 0.8)
v = 1.6(0) ms −1 | M1
A1
M1
A1
A1 | [5] | Uses T = λ × /L (e = 0.064)
(0.8 + 0.064 – 0.82)
Sets up 2EE/2KE/PE equation
(ii) | PE gain to reach O = 0.4 g × 0.82
KE + EE = 0.4 × 1.5 2 /2
+50(0.82 – 0.8) 2 /(2 × 0.8)
Shows by evaluation that insufficient
energy | B1
M1
A1 | [3] | From initial position, (3.28J)
At initial position, (0.4625J) | 8
Page 6 | Mark Scheme | Syllabus | Paper
GCE A LEVEL – October/November 2013 | 9709 | 53
Two particles $A$ and $B$ have masses $3m$ and $2m$ respectively. Initially $A$ is at rest and $B$ is moving with speed $u$ in a straight line towards $A$. The coefficient of restitution between the particles is $e$.

\begin{enumerate}[label=(\roman*)]
\item Find the speeds of the particles immediately after the collision.
\item Find the condition on $e$ for $A$ to be moving faster than $B$ after the collision.
\end{enumerate}
[8]

\hfill \mbox{\textit{CAIE M2 2013 Q6 [8]}}