# Question #3e15b

Sep 4, 2016

19.8 = 9.81 t t=2.01 secs

#### Explanation:

$0 - v = g \left(t - {t}_{0}\right)$
where t is the time at which the maximum height is reached, after the stone is thrown upward, at time ${t}_{0}$. The time taken is of course the difference and we get
$19.8 = 9.81 \left(t - {t}_{0}\right)$
or
$t = 2.01$ secs, as we are free to set ${t}_{0} = 0$ secs. Maximum height is the point where the height ceases to increase, and therefore the vertical velocity is $0$ m/s.