Hello faolan Originally Posted by

**faolan** I want to create a quadratic equation. I understand the form is Ax^2 + Bx + C = 0. However, the instructor says we can use the form y = +/- x^2.

If I wanted to create a quadratic equation simulating a bird falling out of the sky to the earth...where would I begin? I'm not sure what factors to bring into such a question? The initial height? The speed of flight? How do I translate any question regarding a bird falling to hit the earth in this quadratic equation? This is the first time I've studied this stuff at all, so I could use a little direction in construction a word problem.

A body falling freely under gravity (that is, without air resistance - which in the case of a bird falling is a gross assumption!) has a height, $\displaystyle h$, above ground, after time $\displaystyle t$, given by the equation:

$\displaystyle h=ut-\tfrac12gt^2$, where $\displaystyle g$ is the acceleration due to gravity and $\displaystyle u$ is its initial velocity, measured vertically upwards.

This is a quadratic expression in terms of $\displaystyle t$, so you should be able to work out something based on this formula.

Grandad