[SOLVED] Velocity of sound and bomb explosions on TV

[pateldivyesh68@gmail.com]

velocity of sound is proportional to temperature....in air...at o deg ,v1=332m/s... at 20 deg,v2=344m/s....but how its possible in space..?....if bomb blast in air we can see the light first but sound later on....
but in TV ,ther is sound 1st,then video...(in some cases)....how is it possible.??

 

[keith1200rs]

Re: velocity of sound...

I am not quite sure which scenario you are confused with. Don't confuse air/sound as a transmission medium with sound from a TV. With a TV the signal is all transmitted with the same medium - radio waves. It is only the last few feet where it is split back in to sound and light so there is no time difference.

I don't know if that helps but if you could rephrase your question that might help.

Keith

 

[FvM]

Re: velocity of sound...

velocity of sound is proportional to temperature

Not quite right. More exactly: v ~ √T

 

[E Kafeman]

Re: velocity of sound...

On TV are sliding car-tires screaming at wet roads as well as gravel roads, without any delay at all, even if camera view is more then 300 meter away.
In space are no tires needed, but if, I am sure they will scream on TV without delay.
Guess they use unusual sensitive and delay-free microphones for TV-productions.

For a digital coded TV signal is picture often compressed by comparing difference between several frames. For decoding a such signal must a part of signal stream be stored in receiver memory for up to several seconds before it is fully decoded and can be sent to screen.
Also sound can be similar coded but delay is then just a few mS. If nothing is done to correct this will a bomb first be heard and then explode. :roll:

 

[chuckey]

Re: velocity of sound...

In general the sound arrives later then the vision with TV. This is because of the stereo which is coded in a digital format and the encoding takes time to make a decision. A delay should be put in in the vision chain so the viewer gets both together at the right time. The encoding delay is about .25 secs. This delay is also present with "digital" TV. Over here (England) about 10% od digital originated programmes have the incorrect lip-sync.
Frank

 

[enjunear]

Re: velocity of sound...

All sorts of tricks can/are played with TV sounds. Most of the time, the sound effects are added in post-production. Things like screeching car tires, bomb blasts, slaps, punches, bullets, etc. are all pre-recorded, or made in a sound effects studio to fit the needs for a particular show. It's very easy to strip off the original audio tack, make a new audio track, and remux them (mux = multiplex = recombine audio+video streams).

As for an explosion in space... in reality, you'd only see the light, but there would be NO SOUND. That's because sound travels as compression waves through a fluid medium (air, in this case). Since there would be no air in space (it's a vacuum), there is nothing for the sound to propagate through. Therefore, you would hear no sound from an explosion in space.

 

[E Kafeman]

Re: velocity of sound...

Minor sound in outer space, is perhaps possible as it not is absolute vacuum, but tires on a gravel road never ever screech except if it is a us police car in a movie. Special Hollywood tires maybe.

 

[davenn]

Re: velocity of sound...

Minor sound in outer space, is perhaps possible as it not is absolute vacuum, but tires on a gravel road never ever screech except if it is a us police car in a movie. Special Hollywood tires maybe.

incorrect, obviously you have never been involved in car rallying, you can screech tyres on dirt and gravel roads quite happily.

to the OP ... forget about the movies and TV programs portraying sound from spaceships and explosions in space etc. it doesnt happen !!
ONLY in the movies

cheers
Dave

 

[E Kafeman]

Re: velocity of sound...

incorrect, obviously you have never been involved in car rallying, you can screech tyres on dirt and gravel roads quite happily.

Been rallying for some time, about 20 years, and no, I have never screeched any tires on a gravel road. An example, with standard engine in a old and slow very standard Volvo 940:
YouTube - ‪Dackefejden ss1 Daniel Brorson‬‏
No road notes so that was why it was a bit slow in some parts, but did you hear any screech?
If you drive more slow in bends(without attack) or locks brakes before a bend, as first driver in a race (before any gravels comes loose) on salted road then there is a possibility but it would be unskilled dangerous driving.
I normally have about twice as strong engine as in the movie above, which makes it a bit simpler to drive with more attack before the bends, resulting in more gravel sound but I have never heard any screech.
I think you have Hollywood tires on your car.:grin:

 

[peterjmichigan]

Re: velocity of sound...

Refer this pdf once.....

 

[pateldivyesh68@gmail.com]

Re: velocity of sound...

THANK u ...so much...DEAR

 

[davenn]

Re: velocity of sound...

Been rallying for some time, about 20 years, and no, I have never screeched any tires on a gravel road. An example, with standard engine in a old and slow very standard Volvo 940:
YouTube - ‪Dackefejden ss1 Daniel Brorson‬‏
No road notes so that was why it was a bit slow in some parts, but did you hear any screech?
If you drive more slow in bends(without attack) or locks brakes before a bend, as first driver in a race (before any gravels comes loose) on salted road then there is a possibility but it would be unskilled dangerous driving.
I normally have about twice as strong engine as in the movie above, which makes it a bit simpler to drive with more attack before the bends, resulting in more gravel sound but I have never heard any screech.
I think you have Hollywood tires on your car.:grin:

naaa I think you just dont drive fast enough and using a Volvo hahahaa ... where's that real compeditive spirit ??

seriously tho ... squeeling tyres on dirt and gravel roads is pretty easy to do on sharp cornering

cheers
Dave

PS Volvo's in this part of the world are a major joke and their drivers are even worse.

usual comment by most other road users " look out another Volvo user " they are shocking drivers over here

 

[E Kafeman]

Many drivers select this type of car because Volvo is "safe" so you do not need to care about other traffic as much and it do often survives many years and becomes almost as old as the driver.
I am not that old yet.
Sliding in bends (sharp cornering) at a gravel road is just poor, speed reducing and uncontrolled driving.
You can find hours of advanced gravel driving on youtube. You know what sound that never ever occur?
Proof of opposite with a link.
The competitive spirit was at actual stage as closest 15 seconds behind. A lot of brands such as Subaru, BMW, Honda.. but no Holden.
If all are behind, you not need to care about other traffic, that's life as Volvo driver.