This is problem of free falling objects, which can be solved using the formula:
V = sqrt(2gy)
Where v is the velocity upon impact
G is the acceleration due to gravity ( 9.81 m/s2)
Y is the height
Since Venessa is 3.5 m
Y = 30 -3.5 = 26.5 m
V = sqrt(2 (9.81 m/s2) ( 26.5 m))
V = 22.8 m/s