A little girl is standing on a cliff and throws a ball straight down at a speed of 5m/s towards the ground below. How far has it fallen 2.0 seconds after it leaves her hand?

Answer 1

starting at height 0, its height at time t is

-5t - 4.9t^2

If we fudge a bit and approximate gravity with 5 instead of 4.9, then we have

-5t-5t^2 = -5t(1+t)
at t=2, that's -30