18 A particle is moving in a straight line through the origin \(O\)
The displacement of the particle, \(r\) metres, from \(O\), at time \(t\) seconds is given by
$$r = p + 2 t - q \mathrm { e } ^ { - 0.2 t }$$
where \(p\) and \(q\) are constants.
When \(t = 3\), the acceleration of the particle is \(- 1.8 \mathrm {~m} \mathrm {~s} ^ { - 2 }\)
18
- Show that \(q \approx 82\)
18 - The particle has an initial displacement of 5 metres.
Find the value of \(p\)
Give your answer to two significant figures.
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