4.
\begin{figure}[h]
\includegraphics[alt={},max width=\textwidth]{4109fba0-077e-472b-b37f-7ac2e45aacc7-10_680_1218_141_466}
\captionsetup{labelformat=empty}
\caption{Figure 1}
\end{figure}
A small ball, \(P\), of mass 0.8 kg , is held at rest on a smooth horizontal table and is attached to one end of a thin rope.
The rope passes over a pulley that is fixed at the edge of the table.
The other end of the rope is attached to another small ball, \(Q\), of mass 0.6 kg , that hangs freely below the pulley.
Ball \(P\) is released from rest, with the rope taut, with \(P\) at a distance of 1.5 m from the pulley and with \(Q\) at a height of 0.4 m above the horizontal floor, as shown in Figure 1.
Ball \(Q\) descends, hits the floor and does not rebound.
The balls are modelled as particles, the rope as a light and inextensible string and the pulley as small and smooth.
Using this model,
- show that the acceleration of \(Q\), as it falls, is \(4.2 \mathrm {~ms} ^ { - 2 }\)
- find the time taken by \(P\) to hit the pulley from the instant when \(P\) is released.
- State one limitation of the model that will affect the accuracy of your answer to part (a).
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