# Little ripples in water **URL:** \ **Category:** Factual Questions\ **Created:** [April 16, 2002, 12:40am UTC](https://boards.straightdope.com/t/little-ripples-in-water/103850 "2002-04-16T00:40:59Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![eyedea](https://avatars.discourse-cdn.com/v4/letter/e/ed655f/32.png) [@eyedea](https://boards.straightdope.com/u/eyedea)\ **Post date:** [April 16, 2002, 12:40am UTC](https://boards.straightdope.com/t/little-ripples-in-water/103850/1 "2002-04-16T00:40:59Z")
Why is it, that if you throw an object into a body of water the ripples always form a perfect circle every time? ---
**Author:** ![DPWhite](https://avatars.discourse-cdn.com/v4/letter/d/d26b3c/32.png) [@DPWhite](https://boards.straightdope.com/u/DPWhite)\ **Post date:** [April 16, 2002, 12:55am UTC](https://boards.straightdope.com/t/little-ripples-in-water/103850/2 "2002-04-16T00:55:00Z")
Because the velocity of waves from a uniform source in a single medium is constant. In your case, water, presumably in the sink washing dishes or some such, it is about 30 centimeters a second if I recall my experiments in physics for water wave motion from 22 years ago. You would probably find that they a different velocity in a differing viscosity liquid like oil. Light waves, for example, travel slower through water than they do through air, which is slower than a vacuum. ---
**Author:** ![happyheathen](https://avatars.discourse-cdn.com/v4/letter/h/b5e925/32.png) [@happyheathen](https://boards.straightdope.com/u/happyheathen)\ **Post date:** [April 16, 2002, 1:54am UTC](https://boards.straightdope.com/t/little-ripples-in-water/103850/3 "2002-04-16T01:54:12Z")
how about: “Ripples in still water… When there is no pebble tossed, No wind to blow…” ? I know, GD… ---
**Author:** ![DPWhite](https://avatars.discourse-cdn.com/v4/letter/d/d26b3c/32.png) [@DPWhite](https://boards.straightdope.com/u/DPWhite)\ **Post date:** [April 16, 2002, 2:45am UTC](https://boards.straightdope.com/t/little-ripples-in-water/103850/4 "2002-04-16T02:45:36Z")
Yeah, try dropping a pebble in a box of rain and watch the inverted circles bouncing back, it will roll away the dew… ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [April 16, 2002, 7:57am UTC](https://boards.straightdope.com/t/little-ripples-in-water/103850/5 "2002-04-16T07:57:11Z")
Actually, if the water is in a very shallow tray with a sloping bottom (so that one side is shallower than the other) then the ripples will not form a perfect circle. ---
**Author:** ![femtosecond](https://avatars.discourse-cdn.com/v4/letter/f/f08c70/32.png) [@femtosecond](https://boards.straightdope.com/u/femtosecond)\ **Post date:** [April 16, 2002, 5:15pm UTC](https://boards.straightdope.com/t/little-ripples-in-water/103850/6 "2002-04-16T17:15:35Z")
The speed of a wave on (ideal) water is the same in every direction. So in a given period of time a disturbance will spread over the same distance in every direction from its starting point. All points with the same distance to another point lie on a circle. That’s a very fundamental law of nature. You can base many others on it, for instance that a light appears darker and darker if you move away from it.