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Why wouldn't an ASDIC work immediately after a depth charge attack?
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I'm reading about the WW2 North Atlantic submarine war. In particular about the anti-submarine weapons availbale to the allies.
This article includes a statement that I'm trying to understand.....
When a depth charge explodes it can take 15 minutes before the disturbance can settle down enough that sonar becomes effective.
What was the nature of the 'disturbance' that could effect sonar for 15 minutes? I assume it's a reference to some form of underwater echos and/or shockwaves, but if so why so long? I know that sound travels much faster and further in water than air, but does that not mean that any echos should die down more quickly?
Or maybe the ASDIC was very sensitive and needed re-calibration (or even repairs) after a nearby explosion?
Or is there some other phenomena that I've missed?
world-war-two submarine asdic
edited 3 hours ago
AllInOne
1,6272620
asked 5 hours ago
Hemel
38618
add a comment |Â
up vote
2
down vote
favorite
I'm reading about the WW2 North Atlantic submarine war. In particular about the anti-submarine weapons availbale to the allies.
This article includes a statement that I'm trying to understand.....
When a depth charge explodes it can take 15 minutes before the disturbance can settle down enough that sonar becomes effective.
What was the nature of the 'disturbance' that could effect sonar for 15 minutes? I assume it's a reference to some form of underwater echos and/or shockwaves, but if so why so long? I know that sound travels much faster and further in water than air, but does that not mean that any echos should die down more quickly?
Or maybe the ASDIC was very sensitive and needed re-calibration (or even repairs) after a nearby explosion?
Or is there some other phenomena that I've missed?
world-war-two submarine asdic
edited 3 hours ago
AllInOne
1,6272620
asked 5 hours ago
Hemel
38618
It might be better to ask this in physics
– user32121
24 mins ago
add a comment |Â
up vote
2
down vote
favorite
up vote
2
down vote
favorite
I'm reading about the WW2 North Atlantic submarine war. In particular about the anti-submarine weapons availbale to the allies.
This article includes a statement that I'm trying to understand.....
When a depth charge explodes it can take 15 minutes before the disturbance can settle down enough that sonar becomes effective.
What was the nature of the 'disturbance' that could effect sonar for 15 minutes? I assume it's a reference to some form of underwater echos and/or shockwaves, but if so why so long? I know that sound travels much faster and further in water than air, but does that not mean that any echos should die down more quickly?
Or maybe the ASDIC was very sensitive and needed re-calibration (or even repairs) after a nearby explosion?
Or is there some other phenomena that I've missed?
world-war-two submarine asdic
edited 3 hours ago
AllInOne
1,6272620
asked 5 hours ago
Hemel
38618
I'm reading about the WW2 North Atlantic submarine war. In particular about the anti-submarine weapons availbale to the allies.
This article includes a statement that I'm trying to understand.....
When a depth charge explodes it can take 15 minutes before the disturbance can settle down enough that sonar becomes effective.
What was the nature of the 'disturbance' that could effect sonar for 15 minutes? I assume it's a reference to some form of underwater echos and/or shockwaves, but if so why so long? I know that sound travels much faster and further in water than air, but does that not mean that any echos should die down more quickly?
Or maybe the ASDIC was very sensitive and needed re-calibration (or even repairs) after a nearby explosion?
Or is there some other phenomena that I've missed?
world-war-two submarine asdic
world-war-two submarine asdic
edited 3 hours ago
AllInOne
1,6272620
asked 5 hours ago
Hemel
38618
edited 3 hours ago
AllInOne
1,6272620
asked 5 hours ago
Hemel
38618
edited 3 hours ago
AllInOne
1,6272620
edited 3 hours ago
AllInOne
1,6272620
edited 3 hours ago
AllInOne
1,6272620
1,6272620
asked 5 hours ago
Hemel
38618
asked 5 hours ago
Hemel
38618
asked 5 hours ago
Hemel
38618
38618
It might be better to ask this in physics
– user32121
24 mins ago
add a comment |Â
It might be better to ask this in physics
– user32121
24 mins ago
It might be better to ask this in physics
– user32121
24 mins ago
It might be better to ask this in physics
– user32121
24 mins ago
add a comment |Â
3 Answers
3
active
oldest
votes
up vote
2
down vote
To release depth charge ship would have to go below sonar's minimum range
Sonars (or ASDIC in British terminology) were relatively simple in WW2. Sound would be sent in one direction, it would propagate trough the water, and would bounce back from any underwater object in its path (submarine for example). Knowing the speed of sound in the water it was possible to roughly calculate range and bearing of that object. But if the object gets to close to the sonar, it could not detect it. The article about Hedgehog you posted explains that :
The system was developed to solve the problem of the target submarine disappearing from the attacking ship's ASDIC when the ship came within the sonar's minimum range. Due to the speed of sound in water, the time taken for the 'ping' echo to return to the attacking ship from the target submarine became too short to allow the human operator to distinguish the returning audible echo from that of the initial sound pulse emitted by the sonar – the so-called "instantaneous echo", where the output sound pulse and returning echo merge. This "blind spot" allowed the submarine to make evasive manoeuvres undetected while the ship was out of range for depth charge attack. Hence, the submarine was effectively invisible to the sonar as the ship came within the sonar's minimum range. The solution was a weapon mounted on the foredeck that discharged the projectiles up and over that carrying ship's bow, to land in the water some distance in front of the ship while the submarine was still outside the sonar's minimum range.
Depth charges on the other hand were more cumbersome weapons. As you can see from the link, they were usually dropped in the wake of the ship. This means that attacking ship had to cross over submarine, i.e. loose contact for some time. Unlike hedgehogs, depth charges would explode every time (at predetermined depth). Attacking ship would lay pattern of them, wait till they explode, get out of the minimum range and then try to reacquire target providing the cavitation has settled down.
Providing all necessary steps, the fact that sonars rarely worked at speeds above 15 kts and range under 300 yards, plus limitations of sending pings at intervals that lasted around 5 seconds in 5 degree arc (to allow sound to return back) , it could really last up to 15 minutes before you could start search again if first depth charge attack was unsuccessful.
answered 5 hours ago
rs.29
61117
The quote I provided seems to be saying that the sonar physically wouldn't work for 15 minutes, whereas you seem to be saying it might to 15 minutes to re-aquire the target - two subtly different things!
– Hemel
5 hours ago
1
@Hemel Read your quote again : "it can take 15 minutes before the disturbance can settle down enough that sonar becomes effective" . Sonar is working but is not effective.
– rs.29
4 hours ago
add a comment |Â
up vote
2
down vote
I think that the key to this is considering the reflected waves and their interactions with the environment and each other.
The initial explosion will send out shockwaves in all directions. These shockwaves will bounce off any surface, especially the sea floor and the surface with the air. Importantly, these reflected waves will also reflect as they hit any surface (for example, the initial reflection from the seabed will bounce up and reflect from the surface) and those reflections will do the same. As these surfaces are generally going to be irregular so the reflected shockwaves will very quickly become a jumble of noise.
It's also worth considering that depth charges usually dropped in patterns, so there wouldn't be just a single explosion but a series of them. The combination of shockwaves and reflections (and interference between the shockwaves and reflections) will make things very noisy indeed.
The initial explosions are orders of magnitude stronger (i.e. louder) than the ASDIC sound waves, and although each reflection loses energy, it takes time for the reflections to lose sufficient energy that they become insignificant in comparison to the ASDIC signals.
answered 1 hour ago
Steve Bird
11.7k25064
add a comment |Â
up vote
1
down vote
An underwater explosion creates turbulence in the water, creates bubbles, and perhaps mixes waters of varying temperatures or salinities, all of which affect the refraction of sound in water. For ASDIC to work best the water should be homogeneous, with laminar flow only.
answered 5 hours ago
kimchi lover
1,0541413
all true, but would it really take 15 minutes to settle back to normal?
– Hemel
5 hours ago
1
There are obviously many factors involved, the rule-of-thumb-summary of which seems to have been 15 minutes, according to WIkipedia's sources. Isn't your question really an applied physics question and not a history question?
– kimchi lover
5 hours ago
add a comment |Â
3 Answers
3
active
oldest
votes
3 Answers
3
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
2
down vote
To release depth charge ship would have to go below sonar's minimum range
Sonars (or ASDIC in British terminology) were relatively simple in WW2. Sound would be sent in one direction, it would propagate trough the water, and would bounce back from any underwater object in its path (submarine for example). Knowing the speed of sound in the water it was possible to roughly calculate range and bearing of that object. But if the object gets to close to the sonar, it could not detect it. The article about Hedgehog you posted explains that :
The system was developed to solve the problem of the target submarine disappearing from the attacking ship's ASDIC when the ship came within the sonar's minimum range. Due to the speed of sound in water, the time taken for the 'ping' echo to return to the attacking ship from the target submarine became too short to allow the human operator to distinguish the returning audible echo from that of the initial sound pulse emitted by the sonar – the so-called "instantaneous echo", where the output sound pulse and returning echo merge. This "blind spot" allowed the submarine to make evasive manoeuvres undetected while the ship was out of range for depth charge attack. Hence, the submarine was effectively invisible to the sonar as the ship came within the sonar's minimum range. The solution was a weapon mounted on the foredeck that discharged the projectiles up and over that carrying ship's bow, to land in the water some distance in front of the ship while the submarine was still outside the sonar's minimum range.
Depth charges on the other hand were more cumbersome weapons. As you can see from the link, they were usually dropped in the wake of the ship. This means that attacking ship had to cross over submarine, i.e. loose contact for some time. Unlike hedgehogs, depth charges would explode every time (at predetermined depth). Attacking ship would lay pattern of them, wait till they explode, get out of the minimum range and then try to reacquire target providing the cavitation has settled down.
Providing all necessary steps, the fact that sonars rarely worked at speeds above 15 kts and range under 300 yards, plus limitations of sending pings at intervals that lasted around 5 seconds in 5 degree arc (to allow sound to return back) , it could really last up to 15 minutes before you could start search again if first depth charge attack was unsuccessful.
answered 5 hours ago
rs.29
61117
The quote I provided seems to be saying that the sonar physically wouldn't work for 15 minutes, whereas you seem to be saying it might to 15 minutes to re-aquire the target - two subtly different things!
– Hemel
5 hours ago
1
@Hemel Read your quote again : "it can take 15 minutes before the disturbance can settle down enough that sonar becomes effective" . Sonar is working but is not effective.
– rs.29
4 hours ago
add a comment |Â
up vote
2
down vote
To release depth charge ship would have to go below sonar's minimum range
Sonars (or ASDIC in British terminology) were relatively simple in WW2. Sound would be sent in one direction, it would propagate trough the water, and would bounce back from any underwater object in its path (submarine for example). Knowing the speed of sound in the water it was possible to roughly calculate range and bearing of that object. But if the object gets to close to the sonar, it could not detect it. The article about Hedgehog you posted explains that :
The system was developed to solve the problem of the target submarine disappearing from the attacking ship's ASDIC when the ship came within the sonar's minimum range. Due to the speed of sound in water, the time taken for the 'ping' echo to return to the attacking ship from the target submarine became too short to allow the human operator to distinguish the returning audible echo from that of the initial sound pulse emitted by the sonar – the so-called "instantaneous echo", where the output sound pulse and returning echo merge. This "blind spot" allowed the submarine to make evasive manoeuvres undetected while the ship was out of range for depth charge attack. Hence, the submarine was effectively invisible to the sonar as the ship came within the sonar's minimum range. The solution was a weapon mounted on the foredeck that discharged the projectiles up and over that carrying ship's bow, to land in the water some distance in front of the ship while the submarine was still outside the sonar's minimum range.
Depth charges on the other hand were more cumbersome weapons. As you can see from the link, they were usually dropped in the wake of the ship. This means that attacking ship had to cross over submarine, i.e. loose contact for some time. Unlike hedgehogs, depth charges would explode every time (at predetermined depth). Attacking ship would lay pattern of them, wait till they explode, get out of the minimum range and then try to reacquire target providing the cavitation has settled down.
Providing all necessary steps, the fact that sonars rarely worked at speeds above 15 kts and range under 300 yards, plus limitations of sending pings at intervals that lasted around 5 seconds in 5 degree arc (to allow sound to return back) , it could really last up to 15 minutes before you could start search again if first depth charge attack was unsuccessful.
answered 5 hours ago
rs.29
61117
The quote I provided seems to be saying that the sonar physically wouldn't work for 15 minutes, whereas you seem to be saying it might to 15 minutes to re-aquire the target - two subtly different things!
– Hemel
5 hours ago
1
@Hemel Read your quote again : "it can take 15 minutes before the disturbance can settle down enough that sonar becomes effective" . Sonar is working but is not effective.
– rs.29
4 hours ago
add a comment |Â
up vote
2
down vote
up vote
2
down vote
To release depth charge ship would have to go below sonar's minimum range
Sonars (or ASDIC in British terminology) were relatively simple in WW2. Sound would be sent in one direction, it would propagate trough the water, and would bounce back from any underwater object in its path (submarine for example). Knowing the speed of sound in the water it was possible to roughly calculate range and bearing of that object. But if the object gets to close to the sonar, it could not detect it. The article about Hedgehog you posted explains that :
The system was developed to solve the problem of the target submarine disappearing from the attacking ship's ASDIC when the ship came within the sonar's minimum range. Due to the speed of sound in water, the time taken for the 'ping' echo to return to the attacking ship from the target submarine became too short to allow the human operator to distinguish the returning audible echo from that of the initial sound pulse emitted by the sonar – the so-called "instantaneous echo", where the output sound pulse and returning echo merge. This "blind spot" allowed the submarine to make evasive manoeuvres undetected while the ship was out of range for depth charge attack. Hence, the submarine was effectively invisible to the sonar as the ship came within the sonar's minimum range. The solution was a weapon mounted on the foredeck that discharged the projectiles up and over that carrying ship's bow, to land in the water some distance in front of the ship while the submarine was still outside the sonar's minimum range.
Depth charges on the other hand were more cumbersome weapons. As you can see from the link, they were usually dropped in the wake of the ship. This means that attacking ship had to cross over submarine, i.e. loose contact for some time. Unlike hedgehogs, depth charges would explode every time (at predetermined depth). Attacking ship would lay pattern of them, wait till they explode, get out of the minimum range and then try to reacquire target providing the cavitation has settled down.
Providing all necessary steps, the fact that sonars rarely worked at speeds above 15 kts and range under 300 yards, plus limitations of sending pings at intervals that lasted around 5 seconds in 5 degree arc (to allow sound to return back) , it could really last up to 15 minutes before you could start search again if first depth charge attack was unsuccessful.
answered 5 hours ago
rs.29
61117
To release depth charge ship would have to go below sonar's minimum range
Sonars (or ASDIC in British terminology) were relatively simple in WW2. Sound would be sent in one direction, it would propagate trough the water, and would bounce back from any underwater object in its path (submarine for example). Knowing the speed of sound in the water it was possible to roughly calculate range and bearing of that object. But if the object gets to close to the sonar, it could not detect it. The article about Hedgehog you posted explains that :
The system was developed to solve the problem of the target submarine disappearing from the attacking ship's ASDIC when the ship came within the sonar's minimum range. Due to the speed of sound in water, the time taken for the 'ping' echo to return to the attacking ship from the target submarine became too short to allow the human operator to distinguish the returning audible echo from that of the initial sound pulse emitted by the sonar – the so-called "instantaneous echo", where the output sound pulse and returning echo merge. This "blind spot" allowed the submarine to make evasive manoeuvres undetected while the ship was out of range for depth charge attack. Hence, the submarine was effectively invisible to the sonar as the ship came within the sonar's minimum range. The solution was a weapon mounted on the foredeck that discharged the projectiles up and over that carrying ship's bow, to land in the water some distance in front of the ship while the submarine was still outside the sonar's minimum range.
Depth charges on the other hand were more cumbersome weapons. As you can see from the link, they were usually dropped in the wake of the ship. This means that attacking ship had to cross over submarine, i.e. loose contact for some time. Unlike hedgehogs, depth charges would explode every time (at predetermined depth). Attacking ship would lay pattern of them, wait till they explode, get out of the minimum range and then try to reacquire target providing the cavitation has settled down.
Providing all necessary steps, the fact that sonars rarely worked at speeds above 15 kts and range under 300 yards, plus limitations of sending pings at intervals that lasted around 5 seconds in 5 degree arc (to allow sound to return back) , it could really last up to 15 minutes before you could start search again if first depth charge attack was unsuccessful.
answered 5 hours ago
rs.29
61117
answered 5 hours ago
rs.29
61117
answered 5 hours ago
rs.29
61117
answered 5 hours ago
rs.29
61117
61117
The quote I provided seems to be saying that the sonar physically wouldn't work for 15 minutes, whereas you seem to be saying it might to 15 minutes to re-aquire the target - two subtly different things!
– Hemel
5 hours ago
1
@Hemel Read your quote again : "it can take 15 minutes before the disturbance can settle down enough that sonar becomes effective" . Sonar is working but is not effective.
– rs.29
4 hours ago
add a comment |Â
The quote I provided seems to be saying that the sonar physically wouldn't work for 15 minutes, whereas you seem to be saying it might to 15 minutes to re-aquire the target - two subtly different things!
– Hemel
5 hours ago
1
@Hemel Read your quote again : "it can take 15 minutes before the disturbance can settle down enough that sonar becomes effective" . Sonar is working but is not effective.
– rs.29
4 hours ago
The quote I provided seems to be saying that the sonar physically wouldn't work for 15 minutes, whereas you seem to be saying it might to 15 minutes to re-aquire the target - two subtly different things!
– Hemel
5 hours ago
The quote I provided seems to be saying that the sonar physically wouldn't work for 15 minutes, whereas you seem to be saying it might to 15 minutes to re-aquire the target - two subtly different things!
– Hemel
5 hours ago
1
1
@Hemel Read your quote again : "it can take 15 minutes before the disturbance can settle down enough that sonar becomes effective" . Sonar is working but is not effective.
– rs.29
4 hours ago
@Hemel Read your quote again : "it can take 15 minutes before the disturbance can settle down enough that sonar becomes effective" . Sonar is working but is not effective.
– rs.29
4 hours ago
add a comment |Â
up vote
2
down vote
I think that the key to this is considering the reflected waves and their interactions with the environment and each other.
The initial explosion will send out shockwaves in all directions. These shockwaves will bounce off any surface, especially the sea floor and the surface with the air. Importantly, these reflected waves will also reflect as they hit any surface (for example, the initial reflection from the seabed will bounce up and reflect from the surface) and those reflections will do the same. As these surfaces are generally going to be irregular so the reflected shockwaves will very quickly become a jumble of noise.
It's also worth considering that depth charges usually dropped in patterns, so there wouldn't be just a single explosion but a series of them. The combination of shockwaves and reflections (and interference between the shockwaves and reflections) will make things very noisy indeed.
The initial explosions are orders of magnitude stronger (i.e. louder) than the ASDIC sound waves, and although each reflection loses energy, it takes time for the reflections to lose sufficient energy that they become insignificant in comparison to the ASDIC signals.
answered 1 hour ago
Steve Bird
11.7k25064
add a comment |Â
up vote
2
down vote
I think that the key to this is considering the reflected waves and their interactions with the environment and each other.
The initial explosion will send out shockwaves in all directions. These shockwaves will bounce off any surface, especially the sea floor and the surface with the air. Importantly, these reflected waves will also reflect as they hit any surface (for example, the initial reflection from the seabed will bounce up and reflect from the surface) and those reflections will do the same. As these surfaces are generally going to be irregular so the reflected shockwaves will very quickly become a jumble of noise.
It's also worth considering that depth charges usually dropped in patterns, so there wouldn't be just a single explosion but a series of them. The combination of shockwaves and reflections (and interference between the shockwaves and reflections) will make things very noisy indeed.
The initial explosions are orders of magnitude stronger (i.e. louder) than the ASDIC sound waves, and although each reflection loses energy, it takes time for the reflections to lose sufficient energy that they become insignificant in comparison to the ASDIC signals.
answered 1 hour ago
Steve Bird
11.7k25064
add a comment |Â
up vote
2
down vote
up vote
2
down vote
I think that the key to this is considering the reflected waves and their interactions with the environment and each other.
The initial explosion will send out shockwaves in all directions. These shockwaves will bounce off any surface, especially the sea floor and the surface with the air. Importantly, these reflected waves will also reflect as they hit any surface (for example, the initial reflection from the seabed will bounce up and reflect from the surface) and those reflections will do the same. As these surfaces are generally going to be irregular so the reflected shockwaves will very quickly become a jumble of noise.
It's also worth considering that depth charges usually dropped in patterns, so there wouldn't be just a single explosion but a series of them. The combination of shockwaves and reflections (and interference between the shockwaves and reflections) will make things very noisy indeed.
The initial explosions are orders of magnitude stronger (i.e. louder) than the ASDIC sound waves, and although each reflection loses energy, it takes time for the reflections to lose sufficient energy that they become insignificant in comparison to the ASDIC signals.
answered 1 hour ago
Steve Bird
11.7k25064
I think that the key to this is considering the reflected waves and their interactions with the environment and each other.
The initial explosion will send out shockwaves in all directions. These shockwaves will bounce off any surface, especially the sea floor and the surface with the air. Importantly, these reflected waves will also reflect as they hit any surface (for example, the initial reflection from the seabed will bounce up and reflect from the surface) and those reflections will do the same. As these surfaces are generally going to be irregular so the reflected shockwaves will very quickly become a jumble of noise.
It's also worth considering that depth charges usually dropped in patterns, so there wouldn't be just a single explosion but a series of them. The combination of shockwaves and reflections (and interference between the shockwaves and reflections) will make things very noisy indeed.
The initial explosions are orders of magnitude stronger (i.e. louder) than the ASDIC sound waves, and although each reflection loses energy, it takes time for the reflections to lose sufficient energy that they become insignificant in comparison to the ASDIC signals.
answered 1 hour ago
Steve Bird
11.7k25064
answered 1 hour ago
Steve Bird
11.7k25064
answered 1 hour ago
Steve Bird
11.7k25064
answered 1 hour ago
Steve Bird
11.7k25064
11.7k25064
add a comment |Â
add a comment |Â
up vote
1
down vote
An underwater explosion creates turbulence in the water, creates bubbles, and perhaps mixes waters of varying temperatures or salinities, all of which affect the refraction of sound in water. For ASDIC to work best the water should be homogeneous, with laminar flow only.
answered 5 hours ago
kimchi lover
1,0541413
all true, but would it really take 15 minutes to settle back to normal?
– Hemel
5 hours ago
1
There are obviously many factors involved, the rule-of-thumb-summary of which seems to have been 15 minutes, according to WIkipedia's sources. Isn't your question really an applied physics question and not a history question?
– kimchi lover
5 hours ago
add a comment |Â
up vote
1
down vote
An underwater explosion creates turbulence in the water, creates bubbles, and perhaps mixes waters of varying temperatures or salinities, all of which affect the refraction of sound in water. For ASDIC to work best the water should be homogeneous, with laminar flow only.
answered 5 hours ago
kimchi lover
1,0541413
all true, but would it really take 15 minutes to settle back to normal?
– Hemel
5 hours ago
1
There are obviously many factors involved, the rule-of-thumb-summary of which seems to have been 15 minutes, according to WIkipedia's sources. Isn't your question really an applied physics question and not a history question?
– kimchi lover
5 hours ago
add a comment |Â
up vote
1
down vote
up vote
1
down vote
An underwater explosion creates turbulence in the water, creates bubbles, and perhaps mixes waters of varying temperatures or salinities, all of which affect the refraction of sound in water. For ASDIC to work best the water should be homogeneous, with laminar flow only.
answered 5 hours ago
kimchi lover
1,0541413
An underwater explosion creates turbulence in the water, creates bubbles, and perhaps mixes waters of varying temperatures or salinities, all of which affect the refraction of sound in water. For ASDIC to work best the water should be homogeneous, with laminar flow only.
answered 5 hours ago
kimchi lover
1,0541413
answered 5 hours ago
kimchi lover
1,0541413
answered 5 hours ago
kimchi lover
1,0541413
answered 5 hours ago
kimchi lover
1,0541413
1,0541413
all true, but would it really take 15 minutes to settle back to normal?
– Hemel
5 hours ago
1
There are obviously many factors involved, the rule-of-thumb-summary of which seems to have been 15 minutes, according to WIkipedia's sources. Isn't your question really an applied physics question and not a history question?
– kimchi lover
5 hours ago
add a comment |Â
all true, but would it really take 15 minutes to settle back to normal?
– Hemel
5 hours ago
1
There are obviously many factors involved, the rule-of-thumb-summary of which seems to have been 15 minutes, according to WIkipedia's sources. Isn't your question really an applied physics question and not a history question?
– kimchi lover
5 hours ago
all true, but would it really take 15 minutes to settle back to normal?
– Hemel
5 hours ago
all true, but would it really take 15 minutes to settle back to normal?
– Hemel
5 hours ago
1
1
There are obviously many factors involved, the rule-of-thumb-summary of which seems to have been 15 minutes, according to WIkipedia's sources. Isn't your question really an applied physics question and not a history question?
– kimchi lover
5 hours ago
There are obviously many factors involved, the rule-of-thumb-summary of which seems to have been 15 minutes, according to WIkipedia's sources. Isn't your question really an applied physics question and not a history question?
– kimchi lover
5 hours ago
add a comment |Â
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It might be better to ask this in physics
– user32121
24 mins ago