A particle starts from the origin at $t = 0$ under a variable acceleration $\alpha$, it stops at $t = 1$ at $(0,1)$, provided that the motion takes place along the x-axis. Show that:

i) The value of $\alpha$ cannot be positive for all $t \in [0,1]$

ii) $|\alpha| \geq 4$ for some points (or points) in it's path.

While the first part is obvious (as the particle must decelerate for the velocity to come to zero), I couldn't prove the second part.



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