Edexcel M3 2003 January — Question 4 11 marks

Exam BoardEdexcel
ModuleM3 (Mechanics 3)
Year2003
SessionJanuary
Marks11
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicSimple Harmonic Motion
TypeFind period from given information
DifficultyStandard +0.3 This is a standard SHM question requiring application of well-known formulas (v² = ω²(a² - x²), vₘₐₓ = ωa, aₘₐₓ = ω²a) with straightforward algebraic manipulation. Part (d) requires finding time intervals using inverse trig, which is slightly beyond routine but still a common SHM exercise. Slightly above average difficulty due to the multi-part nature and part (d), but all techniques are standard M3 material.
Spec4.10f Simple harmonic motion: x'' = -omega^2 x4.10g Damped oscillations: model and interpret

4. A piston \(P\) in a machine moves in a straight line with simple harmonic motion about a point \(O\), which is the centre of the oscillations. The period of the oscillations is \(\pi \mathrm { s }\). When \(P\) is 0.5 m from \(O\), its speed is \(2.4 \mathrm {~m} \mathrm {~s} ^ { - 1 }\). Find
  1. the amplitude of the motion,
  2. the maximum speed of \(P\) during the motion,
  3. the maximum magnitude of the acceleration of \(P\) during the motion,
  4. the total time, in s to 2 decimal places, in each complete oscillation for which the speed of \(P\) is greater than \(2.4 \mathrm {~m} \mathrm {~s} ^ { - 1 }\).

Question 4:
Part (a):
AnswerMarks Guidance
WorkingMarks Notes
\(\frac{2\pi}{\omega} = \pi \Rightarrow \omega = 2\)B1
\(2.4^2 = 4(a^2 - 0.5^2)\)M1 A1ft
\(a = 1.3\) mA1 (4)
Part (b):
AnswerMarks Guidance
\(v_{\max} = a\omega = 2.6\) ms\(^{-1}\)B1 (1)
Part (c):
AnswerMarks Guidance
\(\text{arct}_{\max} = a\omega^2 = 5.2\) ms\(^{-2}\)B1ft (1)
Part (d):
AnswerMarks Guidance
\(0.5 = 1.3\sin 2t\)M1
\(t = \frac{1}{2}\sin^{-1}\left(\frac{0.5}{1.3}\right)\)M1 A1
Total time \(= 4t = 0.79\) (2 dp)M1 A1 (5)
# Question 4:

## Part (a):
| Working | Marks | Notes |
|---------|-------|-------|
| $\frac{2\pi}{\omega} = \pi \Rightarrow \omega = 2$ | B1 | |
| $2.4^2 = 4(a^2 - 0.5^2)$ | M1 A1ft | |
| $a = 1.3$ m | A1 | (4) |

## Part (b):
| $v_{\max} = a\omega = 2.6$ ms$^{-1}$ | B1 | (1) |

## Part (c):
| $\text{arct}_{\max} = a\omega^2 = 5.2$ ms$^{-2}$ | B1ft | (1) |

## Part (d):
| $0.5 = 1.3\sin 2t$ | M1 | |
| $t = \frac{1}{2}\sin^{-1}\left(\frac{0.5}{1.3}\right)$ | M1 A1 | |
| Total time $= 4t = 0.79$ (2 dp) | M1 A1 | (5) |

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4. A piston $P$ in a machine moves in a straight line with simple harmonic motion about a point $O$, which is the centre of the oscillations. The period of the oscillations is $\pi \mathrm { s }$. When $P$ is 0.5 m from $O$, its speed is $2.4 \mathrm {~m} \mathrm {~s} ^ { - 1 }$. Find
\begin{enumerate}[label=(\alph*)]
\item the amplitude of the motion,
\item the maximum speed of $P$ during the motion,
\item the maximum magnitude of the acceleration of $P$ during the motion,
\item the total time, in s to 2 decimal places, in each complete oscillation for which the speed of $P$ is greater than $2.4 \mathrm {~m} \mathrm {~s} ^ { - 1 }$.
\end{enumerate}

\hfill \mbox{\textit{Edexcel M3 2003 Q4 [11]}}