Our values can be defined like this,



The problem can be solved for part A, through the Work Theorem that says the following,

Where
KE = Kinetic energy,
Given things like that and replacing we have that the work is given by
W = Fd
and kinetic energy by

So,

Clearing F,

Replacing the values


B) The work done by the wall is zero since there was no displacement of the wall, that is d = 0.
C. 90 m
30m per second... and it takes 3 seconds
3x30= 90
Time - 0.792s
acceleration - 9.8m/s2
vertical height - ?
remember that height is in meters
so from the acceleration
9.8 = x
----
0.792*0.792
cross multiply
=6.147m approximately 6.2m