Answer
a) 21.3 meters per second
b) 2.6 seconds
Work Step by Step
a) We simplify the equation for final velocity in order to find the initial velocity:
$v_0 = \sqrt{v_f^2 - 2a\Delta x}$
$v_0 = \sqrt{5^2 - 2(-6.3)(34)}=\fbox{21.3 meters per second}$
b) We find the change in time:
$t = \frac{5-21.3}{-6.3}=\fbox{2.6 seconds}$
