# Homework Help: Kinematics Equations (Basic)

1. Oct 5, 2009

### yoyo2112

1. The problem statement, all variables and given/known data

Pelicans tuck their winds and free fall straight down when diving for fish. Suppose a pelican starts its dive form a height of 20.0 m and cannot change its path once commited (uniform motion). If it takes a fish 0.1 s to perform evasive action, at what min height must it spot the pelican in order to escape

2. Relevant equations

No Clue

3. The attempt at a solution

Stumped

I have tried in numerous times but was away for a lesson and dont have a clue to what is going on

Last edited: Oct 5, 2009
2. Oct 5, 2009

### rl.bhat

Find the time t taken by the pelican to reach the water from 20 m.
Then find the distance covered by the pelican in (t - 0.1) seconds. And proceed.

3. Oct 5, 2009

### 206PiruBlood

You will need $$s=y_{i}+v_{i}t+\frac{1}{2}at^{2}$$

How long does it take the pelican to free fall to the water? How much time before that must the fish react?

4. Oct 5, 2009

### yoyo2112

OO thanks for the reply guys. Do you know where i can get a list of all these equations (kinematics)

5. Oct 5, 2009

### 206PiruBlood

Do you have a textbook?