SPS SPS FM 2020 June — Question 7 8 marks

Exam BoardSPS
ModuleSPS FM (SPS FM)
Year2020
SessionJune
Marks8
TopicDifferential equations
TypeConical geometry differential equations
DifficultyStandard +0.3 This is a standard related rates problem requiring similar triangles to express volume in terms of h, then differentiation and separation of variables. The algebra is straightforward with given leak rate, and part (b) is routine integration with initial conditions. Slightly easier than average due to clear setup and standard technique.
Spec1.07t Construct differential equations: in context1.08k Separable differential equations: dy/dx = f(x)g(y)

7. \begin{figure}[h]
\includegraphics[alt={},max width=\textwidth]{0e7cab3d-c1e6-4420-93b4-eca5af704432-07_591_730_294_735} \captionsetup{labelformat=empty} \caption{Diagram not drawn to scale}
\end{figure} Figure 4
[0pt] [ The volume of a cone of base radius \(r\) and height \(h\) is \(\frac { 1 } { 3 } \pi r ^ { 2 } h\) ]
Figure 4 shows a container in the shape of an inverted right circular cone which contains some water. The cone has an internal base radius of 2.5 m and a vertical height of 4 m .
At time \(t\) seconds
  • the height of the water is \(h \mathrm {~m}\)
  • the volume of the water is \(V \mathrm {~m} ^ { 3 }\)
  • the water is modelled as leaking from a hole at the bottom of the container at a rate of
$$\left( \frac { \pi } { 512 } \sqrt { h } \right) m ^ { 3 } s ^ { - 1 }$$
  1. Show that, while the water is leaking $$h ^ { \frac { 3 } { 2 } } \frac { \mathrm {~d} h } { \mathrm {~d} t } = - \frac { 1 } { 200 }$$ Given that the container was initially full of water
  2. find an equation, in terms of \(h\) and \(t\), to model this situation.

7.

\begin{figure}[h]
\begin{center}
  \includegraphics[alt={},max width=\textwidth]{0e7cab3d-c1e6-4420-93b4-eca5af704432-07_591_730_294_735}
\captionsetup{labelformat=empty}
\caption{Diagram not drawn to scale}
\end{center}
\end{figure}

Figure 4\\[0pt]
[ The volume of a cone of base radius $r$ and height $h$ is $\frac { 1 } { 3 } \pi r ^ { 2 } h$ ]\\
Figure 4 shows a container in the shape of an inverted right circular cone which contains some water.

The cone has an internal base radius of 2.5 m and a vertical height of 4 m .\\
At time $t$ seconds

\begin{itemize}
  \item the height of the water is $h \mathrm {~m}$
  \item the volume of the water is $V \mathrm {~m} ^ { 3 }$
  \item the water is modelled as leaking from a hole at the bottom of the container at a rate of
\end{itemize}

$$\left( \frac { \pi } { 512 } \sqrt { h } \right) m ^ { 3 } s ^ { - 1 }$$
\begin{enumerate}[label=(\alph*)]
\item Show that, while the water is leaking

$$h ^ { \frac { 3 } { 2 } } \frac { \mathrm {~d} h } { \mathrm {~d} t } = - \frac { 1 } { 200 }$$

Given that the container was initially full of water
\item find an equation, in terms of $h$ and $t$, to model this situation.
\end{enumerate}

\hfill \mbox{\textit{SPS SPS FM 2020 Q7 [8]}}