Edexcel P4 2023 October — Question 2

Exam BoardEdexcel
ModuleP4 (Pure Mathematics 4)
Year2023
SessionOctober
TopicNon-constant acceleration

2. \begin{figure}[h]
\includegraphics[alt={},max width=\textwidth]{7f5fc83d-ab7c-4edb-a2c6-7a58f1357d5a-04_271_223_246_922} \captionsetup{labelformat=empty} \caption{Figure 1}
\end{figure} Figure 1 shows a cube which is increasing in size.
At time \(t\) seconds,
  • the length of each edge of the cube is \(x \mathrm {~cm}\)
  • the surface area of the cube is \(S \mathrm {~cm} ^ { 2 }\)
  • the volume of the cube is \(V \mathrm {~cm} ^ { 3 }\)
Given that the surface area of the cube is increasing at a constant rate of \(4 \mathrm {~cm} ^ { 2 } \mathrm {~s} ^ { - 1 }\)
  1. show that \(\frac { \mathrm { d } x } { \mathrm {~d} t } = \frac { k } { x }\) where \(k\) is a constant to be found,
  2. show that \(\frac { \mathrm { d } V } { \mathrm {~d} t } = V ^ { p }\) where \(p\) is a constant to be found.