kaseyface Posted May 10, 2006 Share Posted May 10, 2006 1. The distance between two wave crests in the water is 3 meters. A swimmer notices one wave goes by every six seconds. What is the speed of the wave. 2. There is a delay of 5 seconds between the time you see a flash of lightning and hear the thunder. If the temperature is 20 degrees C, how far away is the lightning strike. I haven't a clue where to start on either of these. Link to comment Share on other sites More sharing options...
ydoaPs Posted May 10, 2006 Share Posted May 10, 2006 for the first one, use [math]v={\lambda}f[/math] where [math]{\lambda}[/math] is the wavelength and f is the frequency. also, T-1=f where T is the period. for the second, you'll need the formula for the speed of sound, but i don't know it off the top of my head. Link to comment Share on other sites More sharing options...
kaseyface Posted May 10, 2006 Author Share Posted May 10, 2006 Well, I got the first one and for the second one, I came up with the speed of sound being 349.16 m/s +/- 0.1 But after that, I'm not quite sure what to do. Link to comment Share on other sites More sharing options...
Klaynos Posted May 10, 2006 Share Posted May 10, 2006 Well, you have a time, and a velocity and want a distance... The time taken by the lightening to get to you can be pretty much disregarded as it'll be tiny... Link to comment Share on other sites More sharing options...
Cloud Posted May 11, 2006 Share Posted May 11, 2006 1) speed (m/s) = wavelength x frequency so . . . (3m) x (how many waves in 1 second - oh - you've work it out) 2) speed of sound (m/s) x 5 seconds = distance (m) Simple eh? Link to comment Share on other sites More sharing options...
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