Janet jumps off a high diving platform with
a horizontal velocity of 2.22 m/s and lands in
the water 1.5 s later.
The acceleration of gravity is 9.8 m/s2 .
a) How high is the platform?
Answer in units of m.
1 answer

Her horizontal velocity does not affect the time it takes to fall.
Solve
H = (g/2) t^2
t is the time it takes to fall and you know what g is.
H is the answer