# A man stands on a crane and throws a water balloon down at at 21 m/s. He finds that it takes 2.4s for the balloon to hit the ground. What is its height one second before it hits the ground?

##### 1 Answer

We know that the initial velocity is

One second before it hits the ground implies

What we don't know is the final height after

#= 1/2(9.80665)(2.4)^2 " m" + (21)(2.4) " m"#

#= "78.643 m"#

Now we can use that as the initial height and re-solve for the final height, after determining the partial fall distance.

#= 1/2(9.80665)(1.4)^2 " m" + (21)(1.4) " m" #

#= "39.010 m"#

Finally, treating the ground as