Associated Topics || Dr. Math Home || Search Dr. Math

### Applications of Parabolas

```
Date: 10/24/2000 at 14:57:09
From: Alex Lau
Subject: How parabolas are used in real life.

My question is; how are parabolas used in real life?

I have tried to find this answer through several math sites and books,
but have not found any satisfactory applications. If you could help me
on this subject, that would be wonderful.

Thank you.
```

```
Date: 10/24/2000 at 17:09:21
From: Doctor Ian
Subject: Re: How parabolas are used in real life.

Hi Alex,

Parabolas have some interesting properties. If you put a light at a
particular point (called the "focus") of a parabolic mirror, particles
of light start moving away from the light in all directions, but after
bouncing off the mirror they all move in the same direction, which
means that you can shine the light on something very far away. This is
how a headlight on a car works.

This also means that if you have particles of light that are coming
from very far away, all moving in the same direction - for example,
coming from a star in the sky - then no matter where those particles
bounce off of a parabolic mirror, they all end up in the same place -
at the focus. So you can collect a lot of light from something that
appears very dim to the eye. This is how a telescope works.

The same principles are used to construct the satellite dishes that

A microphone at the focus of a parabolic mirror can be used to listen
to a conversation at a great distance. This is one of the ways that
sportscasters can listen in on what's being said when the coach pulls
his players over to the sideline during a time-out.

Basically, whenever you want to transform radial motion (motion to or
from a central point) into parallel motion or vice versa, a parabolic
mirror is the tool for the job.

There are certainly all kinds of applications for this kind of
transformation that haven't even been thought of yet. For example, if
gravity really is just the exchange of particles (gravitons) that are
sent out in all directions, then a mirror made from a material that
would reflect gravitons could be used to channel all the gravitational
attraction from a lump of mass in a particular direction - which
would be useful for constructing the kind of "tractor beam" that
you're always hearing about on Star Trek...

I hope this helps.

- Doctor Ian, The Math Forum
http://mathforum.org/dr.math/
```
Associated Topics:
High School Basic Algebra
High School Conic Sections/Circles
High School Geometry
High School Practical Geometry

Search the Dr. Math Library:

 Find items containing (put spaces between keywords):   Click only once for faster results: [ Choose "whole words" when searching for a word like age.] all keywords, in any order at least one, that exact phrase parts of words whole words

Submit your own question to Dr. Math
Math Forum Home || Math Library || Quick Reference || Math Forum Search