# Question #5b174

Mar 26, 2015

To solve this problem let's first determine how long it would take an object in free fall to travel 20 m. Next, we'll figure out how far the object will fall in 0.1 seconds less time.

Time to fall from rest can be determined using this equation:
$t = \sqrt{\frac{2 d}{a}}$

Let's take the acceleration of gravity to be
$a = 9.8 \frac{m}{s}$

And the distance is:
$d = 20 m$

So the time to fall is:
$t = \sqrt{\frac{2 \cdot 20}{9.8}} = 2.02 s$

Now lets find out how far something falls in $2.02 - 0.1$ seconds.

$d = \frac{1}{2} a {t}^{2}$
$d = \frac{1}{2} \cdot 9.8 \cdot {1.92}^{2} = 18.06 m$

So we can see that the pelican will cover the last 1.94 meters in just 0.1 seconds. If the fish is able to spot the pelican and react while it is still 1.94 meters above the surface, it just might escape.