Functions

Functions

The velocity \(\mathrm{v}\) ms\(^{-1}\) of a particle at time \(t\) seconds, is given by \(\mathrm{v} = 2t + \cos{2t}\), for \(0 \leq t \leq2\).

  1. Write down the velocity of the particle when \(t = 0\).

When \(t = k\), the acceleration is zero.

    1. Show that \(k = \frac{\pi}{4}\).
    2. Find the exact velocity when \(t = \frac{\pi}{4}\).
  1. When \(t < \frac{\pi}{4}\) ,\(\frac{\mathrm{d}v}{\mathrm{d}t} > 0\) and when \(t > \frac{\pi}{4}\),\(\frac{\mathrm{d}v}{\mathrm{d}t} > 0\)
    Sketch a graph of \(\mathrm{v}\) against \(t\).
  2. Let \(d\) be the distance travelled by the particle for \(0 \leq t \leq 1\).
    1. Write down an expression for \(d\).
    2. Represent \(d\) on your sketch.

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Answer:(a) \(1\text{ m s}^{-1}\) (b)(i) \(k=\dfrac\pi4\) (b)(ii) \(\dfrac\pi2\text{ m s}^{-1}\) (c) increasing graph with stationary point of inflection \(\left(\dfrac\pi4,\dfrac\pi2\right)\) (d)(i) \(d=\displaystyle\int_0^1(2t+\cos2t)\,\mathrm dt=1+\dfrac12\sin2\text{ m}\) (d)(ii) the shaded area under the curve for \(0\le t\le1\)

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