CAIE Further Paper 3 2020 June — Question 5 8 marks

Exam BoardCAIE
ModuleFurther Paper 3 (Further Paper 3)
Year2020
SessionJune
Marks8
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TopicVariable acceleration (1D)
TypeAcceleration as function of velocity (separation of variables)
DifficultyChallenging +1.2 This is a variable acceleration problem requiring separation of variables and integration. Part (a) involves solving a standard first-order ODE (dv/dt = 3ku - kv) which separates cleanly. Part (b) requires using v dv/dx and integrating again. While it's Further Maths content and requires multiple integration steps, the differential equations are straightforward with no tricks—a competent FM student would recognize this as a standard exercise in their syllabus. The 8 total marks reflect routine application rather than novel problem-solving.
Spec6.06a Variable force: dv/dt or v*dv/dx methods

A particle \(P\) is moving along a straight line with acceleration \(3ku - kv\) where \(v\) is its velocity at time \(t\), \(u\) is its initial velocity and \(k\) is a constant. The velocity and acceleration of \(P\) are both in the direction of increasing displacement from the initial position.
  1. Find the time taken for \(P\) to achieve a velocity of \(2u\). [3]
  2. Find an expression for the displacement of \(P\) from its initial position when its velocity is \(2u\). [5]

A particle $P$ is moving along a straight line with acceleration $3ku - kv$ where $v$ is its velocity at time $t$, $u$ is its initial velocity and $k$ is a constant. The velocity and acceleration of $P$ are both in the direction of increasing displacement from the initial position.

\begin{enumerate}[label=(\alph*)]
\item Find the time taken for $P$ to achieve a velocity of $2u$. [3]
\item Find an expression for the displacement of $P$ from its initial position when its velocity is $2u$. [5]
\end{enumerate}

\hfill \mbox{\textit{CAIE Further Paper 3 2020 Q5 [8]}}