Which wave would you observe first?

[jewilki1]

when lightning occurs in the sky, energy is released through the electronic relaxation of nitrogen. This energy can be observed as visible light and can be heard as sound waves (thunder). If you were 10 km from the lightning strike, which wave would you observe first? You must justify your answer and must include a calculation(s). Assume that the sound has a frequency of 100 Hz and and a wavelength 3.5 m. Assume that the visible light has a wavelength of 510 nm.

This comes from problems of the day. We get no solutions, but we have to use these to study for tests. Could you please help me set up these equations. Thanks.

 

[radman]

Help

Well there is a few equations you would use here being
velocity=distance/time
velocity=frequency * lambda
so you would find the speed of both, then you would rearrange velocity=distance/time and see which has the smallest time
Cheers
Kyle

 

[Astronuc]

One needs to compared the speed of light with the speed of sound.

Speed of light 3 x 10⁸ m/s

Speed of sound in air ~350 m/s (~1150 ft/s) at an air temp of 30°C.

t = d/v, where d is distance (e.g. 10 km) and v = speed.

For speed of sound or light, see -

http://hyperphysics.phy-astr.gsu.edu/hbase/sound/souspe.html

http://hyperphysics.phy-astr.gsu.edu/hbase/relativ/ltrans.html#c3