Edexcel M3 2003 January — Question 2 9 marks

Exam BoardEdexcel
ModuleM3 (Mechanics 3)
Year2003
SessionJanuary
Marks9
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicCircular Motion 1
TypeSmooth ring on rotating string
DifficultyStandard +0.3 This is a standard M3 circular motion problem requiring resolution of forces and application of F=mrω². The geometry is straightforward (3-4-5 triangle), and the method is routine for this topic. Part (c) requires minimal conceptual understanding. Slightly easier than average due to the simple geometry and standard technique.
Spec6.04b Find centre of mass: using symmetry6.04c Composite bodies: centre of mass6.05b Circular motion: v=r*omega and a=v^2/r6.05c Horizontal circles: conical pendulum, banked tracks

2. \begin{figure}[h]
\captionsetup{labelformat=empty} \caption{Figure 2} \includegraphics[alt={},max width=\textwidth]{044c5866-0a12-4309-8ced-b463e1615fb0-2_389_601_1362_693}
\end{figure} A light inextensible string of length \(8 l\) has its ends fixed to two points \(A\) and \(B\), where \(A\) is vertically above \(B\). A small smooth ring of mass \(m\) is threaded on the string. The ring is moving with constant speed in a horizontal circle with centre \(B\) and radius 3l, as shown in Fig. 2. Find
  1. the tension in the string,
  2. the speed of the ring.
  3. State briefly in what way your solution might no longer be valid if the ring were firmly attached to the string.
    (1) \section*{3.} \section*{Figure 3}
    \includegraphics[max width=\textwidth, alt={}]{044c5866-0a12-4309-8ced-b463e1615fb0-3_564_1051_438_541}
    A child's toy consists of a uniform solid hemisphere attached to a uniform solid cylinder. The plane face of the hemisphere coincides with the plane face of the cylinder, as shown in Fig. 3. The cylinder and the hemisphere each have radius \(r\), and the height of the cylinder is \(h\). The material of the hemisphere is 6 times as dense as the material of the cylinder. The toy rests in equilibrium on a horizontal plane with the cylinder above the hemisphere and the axis of the cylinder vertical.

2.

\begin{figure}[h]
\begin{center}
\captionsetup{labelformat=empty}
\caption{Figure 2}
  \includegraphics[alt={},max width=\textwidth]{044c5866-0a12-4309-8ced-b463e1615fb0-2_389_601_1362_693}
\end{center}
\end{figure}

A light inextensible string of length $8 l$ has its ends fixed to two points $A$ and $B$, where $A$ is vertically above $B$. A small smooth ring of mass $m$ is threaded on the string. The ring is moving with constant speed in a horizontal circle with centre $B$ and radius 3l, as shown in Fig. 2. Find
\begin{enumerate}[label=(\alph*)]
\item the tension in the string,
\item the speed of the ring.
\item State briefly in what way your solution might no longer be valid if the ring were firmly attached to the string.\\
(1)

\section*{3.}
\section*{Figure 3}
\begin{center}
\includegraphics[max width=\textwidth, alt={}]{044c5866-0a12-4309-8ced-b463e1615fb0-3_564_1051_438_541}
\end{center}

A child's toy consists of a uniform solid hemisphere attached to a uniform solid cylinder. The plane face of the hemisphere coincides with the plane face of the cylinder, as shown in Fig. 3. The cylinder and the hemisphere each have radius $r$, and the height of the cylinder is $h$. The material of the hemisphere is 6 times as dense as the material of the cylinder. The toy rests in equilibrium on a horizontal plane with the cylinder above the hemisphere and the axis of the cylinder vertical.
\end{enumerate}

\hfill \mbox{\textit{Edexcel M3 2003 Q2 [9]}}