# Question #37d9b

$a \equiv \frac{\mathrm{dv}}{\mathrm{dt}}$
In the horizontal direction it is given that velocity is constant and is equal to ${v}_{x}$
$\therefore {a}_{x} = \frac{d}{\mathrm{dt}} \left({v}_{x}\right)$
$\implies {a}_{x} = 0$