2018 TWO(b)

Achievement
Question
A particle is travelling in a straight line. The distance, in metres, travelled by the particle may
be modelled by the function

s(t)=ln(3t2+3t+1)s(t)=\ln(3t^2+3t+1)

t0t\geq 0

where tt is time measured in seconds.

Find the velocity of this particle after 2 seconds.

*You must use calculus and show any derivatives that you need to find when solving this
problem.*
Official Answer
v(t)=6t+33t2+3t+1v'(t)=\dfrac{6t+3}{3t^2+3t+1}

v(2)=1519v'(2)=\dfrac{15}{19} or 0.789 m s10.789\ \text{m s}^{-1}
Grading Criteria

Achievement (u)

  • Correct solution with correct derivative.

Merit (r)

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Excellence T1

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Excellence T2

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Video Explanation
NCEA Level 3 Calculus Differentiation 2018 NZQA Exam - Worked Answers by infinityplusone(starts at 21:39)
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