Alexia is doing some injury prevention and power work in the high performance center. In doing a drop jump, she drops from a set height of $0\mathrm{.}38$ m above the ground and then immediately jumps back into the air as high and as fast as she can. When Alexia leaves the ground to jump up$,$ her vertical velocity is $4\mathrm{.}2$ m$/$s$.$

a$)$ What impulse did Alexia experience while she was in contact with the ground, if her mass was $62$ kg$?$ Answer for part $1$ Ns $(2$ pt$)$

b$)$ What average net force acted on Alexia if she was in contact with the ground for $0\mathrm{.}45$ seconds? Answer for part $2$ N $(1$ pt$)$

c$)$ What was the maximum change in height experienced by Alexia's Centre of Gravity after she left the ground? Answer for part $3$ m $(1$ pt$)$

d$)$ What was the average reaction force $($Force Normal$)$ exerted upwards on Alexia by the ground during the $0\mathrm{.}45$ seconds? Answer for part $4$ N $(1$ pt$)$