# 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. How far has the balloon fallen when it is travelling 40.3 m/s?

##### 1 Answer

The balloon has fallen **60.4 meters**.

#### Explanation:

You know that the ballon was *thrown* where the man sits with an initial velocity of **21 m/s**.

Moreover, you know that it took the balloon **2.4 seconds** to hit the ground. To figure out the distance it travelled when its velocity was equal to **40.3 m/s**, you need to use the formula

#v^2 = v_0^2 + 2 * g * h" "# , where

Rearrange that equation to solve for

#h = (v^2 - v_0^2)/(2 * g)#

#h = ((40.3""^2 - 21^2)"m"^color(red)(cancel(color(black)(2)))/color(red)(cancel(color(black)("s"^2))))/(2 * 9.8color(red)(cancel(color(black)("m")))/color(red)(cancel(color(black)("s"^2)))) = color(green)("60.4 m")#