Because jumping 0.8m from10m height can be regarded as a free fall from10.8m height.
So: t = (vt-v 0)/g (t and 0 after v are subscripts)
T= 14/9.8= 1.43 seconds.
Plus the initial 0.8 m: slow down and vomit.
S = 1/2gt 2 calculates that t is 0.40s, so the total time is1.83s..
(2)
Because it is a free fall, the change is 9.8m/s 2.
(3)
S= 1/2gt^2
S = 5.8m
g=9.8m/s^2
Substitute and calculate t= 1. 1.