# Question #3b038

Nov 7, 2017

12 sec

#### Explanation:

Consider this formula:

$D = {v}_{i} t + 0.5 a {t}^{2}$

The initial velocity ${v}_{i}$ is ZERO

Since the first term of the equation canceled,we can work out the time by using the second part.

$D = 0.5 a {t}^{2}$

${t}^{2} = \frac{D}{0.5 a} = \frac{2 D}{a}$

$t = \sqrt{\frac{2 D}{a}}$

plug in the numbers into the equation to get the answer.
$t = \sqrt{\frac{2 \cdot 245}{3.44}} = 11.93 \ldots$ (s).