CAIE M2 2014 June — Question 1 3 marks

Exam BoardCAIE
ModuleM2 (Mechanics 2)
Year2014
SessionJune
Marks3
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicHooke's law and elastic energy
TypeVertical elastic string: released from rest, string starts taut
DifficultyStandard +0.3 This is a standard energy conservation problem with elastic strings requiring students to identify the slack point (natural length), apply conservation of energy between two positions, and solve for speed. While it involves multiple energy forms (gravitational PE, elastic PE, kinetic), the setup is straightforward with clearly defined positions and no geometric complications or proof elements.
Spec6.02i Conservation of energy: mechanical energy principle6.02j Conservation with elastics: springs and strings

1 A light elastic string has modulus of elasticity 5 N and natural length 1.5 m . One end of the string is attached to a fixed point \(O\) and a particle \(P\) of mass 0.1 kg is attached to the other end of the string. \(P\) is released from rest at the point 2.4 m vertically below \(O\). Calculate the speed of \(P\) at the instant the string first becomes slack.

Question 1:
AnswerMarks Guidance
WorkingMark Guidance
\(EE = 5 \times (2.4-1.5)^2 / (2 \times 15)\)B1
\(5 \times (2.4-1.5)^2 /\)M1 EE/KE/PE conservation
\((2 \times 1.5) - 0.1g \times (2.4-1.5) = 0.1v^2/2\)
\(v = 3 \text{ ms}^{-1}\)A1 [3]
## Question 1:

| Working | Mark | Guidance |
|---------|------|----------|
| $EE = 5 \times (2.4-1.5)^2 / (2 \times 15)$ | B1 | |
| $5 \times (2.4-1.5)^2 /$ | M1 | EE/KE/PE conservation |
| $(2 \times 1.5) - 0.1g \times (2.4-1.5) = 0.1v^2/2$ | | |
| $v = 3 \text{ ms}^{-1}$ | A1 | [3] |

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1 A light elastic string has modulus of elasticity 5 N and natural length 1.5 m . One end of the string is attached to a fixed point $O$ and a particle $P$ of mass 0.1 kg is attached to the other end of the string. $P$ is released from rest at the point 2.4 m vertically below $O$. Calculate the speed of $P$ at the instant the string first becomes slack.

\hfill \mbox{\textit{CAIE M2 2014 Q1 [3]}}