\textbf{157.} A particle moves on a plane and its position vector in SI units is given by $\vec{r} = (6t)\hat{i} + (-t^2 + 4t)\hat{j}$. At the moment $t = 1\ \text{s}$, the velocity vector makes what angle (in degrees) with the positive x-axis?
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(1) $30$ \hfill (2) $0$ \hfill (3) $60$ \hfill (4) $90$
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