1 An object C is moving along a vertical straight line. Fig. 1 shows the velocity-time graph for part of its motion. Initially C is moving upwards at \(14 \mathrm {~m} \mathrm {~s} ^ { - 1 }\) and after 10 s it is moving downwards at \(6 \mathrm {~m} \mathrm {~s} ^ { - 1 }\).
\begin{figure}[h]
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\caption{Fig. 1}
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C then moves as follows.
- In the interval \(10 \leqslant t \leqslant 15\), the velocity of C is constant at \(6 \mathrm {~m} \mathrm {~s} ^ { - 1 }\) downwards.
- In the interval \(15 \leqslant t \leqslant 20\), the velocity of C increases uniformly so that C has zero velocity at \(t = 20\).
- Complete the velocity-time graph for the motion of C in the time interval \(0 \leqslant t \leqslant 20\).
- Calculate the acceleration of C in the time interval \(0 < t < 10\).
- Calculate the displacement of C from \(t = 0\) to \(t = 20\).