Army Rumour Service

Register a free account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members through your own private inbox!

Are we living in a new Dark Age?

Question directed to all the enlightened ones out there:- A rock weighing several tons, lets say 10, travelling, at lets say, 50,000MPH, hits hard earth, what is its explosive yeald, how big would the crater be, and how far from ground zero would the destruction spread... Same question in open water?

(If it hits Birmingham (UK) then that's a bonus.)

That would not be particularly destructive. It would be a right bastard if it hit you and would certainly ruin your day. It probably wouldn't even form a crater (maybe a few very small ones from fragments).

But based on your question and making a few assumptions in line with the question (assuming a 2M wide meteorite of average density, say 2000kg/m^3 hitting sedimentary rock (most likely for an impact on land) at 90 degrees (worst case) then its as follows:

Distance from Impact: 10.00 km ( = 6.21 miles )
Projectile diameter: 2.00 meters ( = 6.56 feet )
Projectile Density: 2000 kg/m3
Impact Velocity: 22.00 km per second (= 50,000 mph)
Impact Angle: 90 degrees
Target Density: 2500 kg/m3
Target Type: Sedimentary Rock​
Energy:
Energy before atmospheric entry: 2.03 x 1012 Joules = 0.48 x 10-3 MegaTons TNT
The average interval between impacts of this size somewhere on Earth is 0.3 years
Major Global Changes:
The Earth is not strongly disturbed by the impact and loses negligible mass.​
The impact does not make a noticeable change in the tilt of Earth's axis (< 5 hundreths of a degree).​
The impact does not shift the Earth's orbit noticeably.​
Atmospheric Entry:
The projectile begins to breakup at an altitude of 69700 meters = 229000 ft
The projectile bursts into a cloud of fragments at an altitude of 51400 meters = 169000 ft
The residual velocity of the projectile fragments after the burst is 20.1 km/s = 12.5 miles/s
The energy of the airburst is 3.43 x 1011 Joules = 0.82 x 10-4 MegaTons.​
No crater is formed, although large fragments may strike the surface​
.Air Blast:
The air blast will arrive approximately 2.65 minutes after impact.​
Peak Overpressure: 32.6 - 65.2 Pa = 0.000326 - 0.000652 bars = 0.00463 - 0.00926 psi
Max wind velocity: 0.0769 m/s = 0.172 mph
Sound Intensity: 30 dB (Easily Heard)

Imperial College have an impact calculator here:

To ethnically cleanse Brum (of all ethnicities) you need to think bigger. Much bigger than your hypothetical tiddler.
 
That would not be particularly destructive. It would be a right bastard if it hit you and would certainly ruin your day. It probably wouldn't even form a crater (maybe a few very small ones from fragments).

But based on your question and making a few assumptions in line with the question (assuming a 2M wide meteorite of average density, say 2000kg/m^3 hitting sedimentary rock (most likely for an impact on land) at 90 degrees (worst case) then its as follows:

Distance from Impact: 10.00 km ( = 6.21 miles )
Projectile diameter: 2.00 meters ( = 6.56 feet )
Projectile Density: 2000 kg/m3
Impact Velocity: 22.00 km per second (= 50,000 mph)
Impact Angle: 90 degrees
Target Density: 2500 kg/m3
Target Type: Sedimentary Rock​
Energy:
Energy before atmospheric entry: 2.03 x 1012 Joules = 0.48 x 10-3 MegaTons TNT
The average interval between impacts of this size somewhere on Earth is 0.3 years
Major Global Changes:
The Earth is not strongly disturbed by the impact and loses negligible mass.​
The impact does not make a noticeable change in the tilt of Earth's axis (< 5 hundreths of a degree).​
The impact does not shift the Earth's orbit noticeably.​
Atmospheric Entry:
The projectile begins to breakup at an altitude of 69700 meters = 229000 ft
The projectile bursts into a cloud of fragments at an altitude of 51400 meters = 169000 ft
The residual velocity of the projectile fragments after the burst is 20.1 km/s = 12.5 miles/s
The energy of the airburst is 3.43 x 1011 Joules = 0.82 x 10-4 MegaTons.​
No crater is formed, although large fragments may strike the surface​
.Air Blast:
The air blast will arrive approximately 2.65 minutes after impact.​
Peak Overpressure: 32.6 - 65.2 Pa = 0.000326 - 0.000652 bars = 0.00463 - 0.00926 psi
Max wind velocity: 0.0769 m/s = 0.172 mph
Sound Intensity: 30 dB (Easily Heard)

Imperial College have an impact calculator here:

To ethnically cleanse Brum (of all ethnicities) you need to think bigger. Much bigger than your hypothetical tiddler.


Many thanks for your very detailed answer, I can only assume that the asteroid that is about to hit earth, will do negligible damage if it impacts open land, on a city, that's another topic for discussion.

Late Edit:- If it hit Birmingham, apart from the damage, who would notice the difference?
 
Many thanks for your very detailed answer, I can only assume that the asteroid that is about to hit earth, will do negligible damage if it impacts open land, on a city, that's another topic for discussion.

Late Edit:- If it hit Birmingham, apart from the damage, who would notice the difference?

The one en route would probably be like the one detailed above. It is unlikely it would damage a city as it would be broken up into small fragments thirty miles up.

It would be like that one in Russia a few years ago (but much smaller). That was 20m wide and caused an air burst about 19 miles up.

There were injuries and damage but nothing catastrophic.

The really frightening thing about that one was we didn't know about it until it hit us.
 
True but, apparently, I can refute your assertion by kicking a nearby rock!

I don't understand the point you are making. I didn't make an assertion.

However, taking your post at face value, it is fairly easy to develop a Theory Of Rock Kicking.

Hypothesis: Will kicking a rock hurt my foot. Null hypothesis is that it won't (after all kicking the cat or a football doesn't hurt).

Experiment: Kick rock very hard twenty times. Measure resulting pain.

Results: Yes it really ******* hurts if you kick a rock very hard twenty times. Null hypothesis rejected with very high level of confidence.

Theory: Kicking a rock very hard hurts. It's not falsifiable, its based on evidence and it can be used to make predictions.
 
Top