# The Naked Scientists Forum

### Author Topic: Is light that much faster than sound?  (Read 5738 times)

#### OmnipotentOne

• Sr. Member
• Posts: 146
##### Is light that much faster than sound?
« on: 14/06/2004 03:20:00 »
When I go out shopping or just hanging out, contemplating the smallest unit of existance in my coffee isnt on my agenda.  But for some reason at a fair earlier today i couldnt help myself to start thinking about how people say time stands still at the speed of light.  At that time i was watching fireworks and kinda got distracted.  With the thought still lingering in my mind I'd watch the firework zoom up, explode with magnificent array of light, then shortly following id hear boom that shook the ground.  But then it hit me, from the time the firework explodes until the time i hear the sound is about 2.5 seconds, is that really the difference in the speed of sound, to the speed of light.   I'm not positive but the speed of light is around 576 million mph (its wrong i know)

Is light that much faster than sound??  IS sound really that reliable to tell how far somthing is away?

Oh yeah please excuse my spelling![:p]

To see the world through a grain of sand.
« Last Edit: 30/06/2004 09:40:07 by Exodus »

#### gsmollin

• Hero Member
• Posts: 749
##### Re: Is light that much faster than sound?
« Reply #1 on: 14/06/2004 04:40:12 »
The speed of light is 186,000 miles/sec. The speed of sound, in air at sea level is about 1100 ft/sec = 0.21 miles/sec. As you can see, light travels from the fireworks to you essentially in an instant. The sound wave takes 2.5 seconds, at 0.21 miles/sec. to reach your ear. The fireworks were 0.21*2.5=0.53 miles away. The light traveled that same distance in 2.8 microseconds.

#### neilep

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##### Re: Is light that much faster than sound?
« Reply #2 on: 14/06/2004 10:28:27 »
Yea....sound is well slow compared to light....but am I right in thinking that sound travels much faster underwater gsmollin ? (but still fails dismally in comparison to light)

'Men are the same as women...just inside out !'

#### gsmollin

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##### Re: Is light that much faster than sound?
« Reply #3 on: 14/06/2004 17:23:42 »
Yes, much faster underwater. If memory serves, about 4.6 km/s. (15,000 feet/s). In very stiff materials, like steel, it really gets sped up, but I don't recall the figure(s). Also, in a solid, sound can exist as longitudinal or transverse waves. That's how the density of the earth is measured, and whether its a solid or a liquid, incidentally.

#### OmnipotentOne

• Sr. Member
• Posts: 146
##### Re: Is light that much faster than sound?
« Reply #4 on: 15/06/2004 03:34:40 »
Hmmm thanks guys!

I never knew sound could travel at such a higher speed in denser objects, cool!

To see the world through a grain of sand.

#### Dan B

• Jr. Member
• Posts: 49
##### Re: Is light that much faster than sound?
« Reply #5 on: 15/06/2004 03:56:38 »
But, light travels slower in denser objects....

#### The Naked Scientists Forum

##### Re: Is light that much faster than sound?
« Reply #5 on: 15/06/2004 03:56:38 »