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Wargaming does not understand physics :P


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murn123 #1 Posted 19 October 2019 - 02:35 PM

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It has come to my attention that wargaming in simulating ramming damage is making one of the most common cardinal sins.

 

Block Quote

 

Ramming Damage

You can also damage a target by ramming it. The collision creates an explosion at the point of impact similar to that of a high-explosive shell. The strength of the explosion, i.e. the damage potential, depends on the kinetic energy applied in the collision (0.5 * combined weight * relative speed^2), or in other words the combined weight of you and your target as well as your relative speed. That means that the heavier both you and your target are and the faster you collide, the stronger the explosion caused by the collision will be.

However, that damage potential is distributed according to the weight of each of the two colliding vehicles relative to their combined weight (1 - individual weight / combined weight). For example, if you weigh 75 tons and you ram a target weighing 25 tons, only 25% of the explosion will affect you.

Actual damage calculation then follows the same rules as for high-explosive shell explosions, thus ramming lightly armoured targets/areas of the target will cause more damage than strongly armoured parts. Damage taken can be reduced by having a Spall Liner equipped. You can further reduce damage taken and at the same time increase the damage inflicted to the target by having your vehicle's Driver trained in the Controlled Impact skill.

If you are about to be rammed, you can reduce the damage you will take by moving away from the approaching enemy, thus reducing your relative speed, and pointing your strongest armour at them. If your Driver has the Controlled Impact skill, you need to be moving to activate it, anyway.

 In the first paragraph they make a huge mistake in kinetic energy application : kinetic energy applied in the collision (0.5 * combined weight * relative speed^2), by introducing relative speed. by their logic if a tank going 60 km/h hits a tank going 40 km/h the whole kinetic energy is a square of 100 km/h, making collsision way too dangerous. This simplification of realtive speed also makes collision where one tank is backing away way too safe, for the same reason as before.

Also their simplification of combined weight increases energy for no reason when one of the tanks is stationary. 

 

Yes, I understand that this is simplification, but it just seems unnecessary.

 



Dava_117 #2 Posted 19 October 2019 - 02:40 PM

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View Postmurn123, on 19 October 2019 - 02:35 PM, said:

It has come to my attention that wargaming in simulating ramming damage is making one of the most common cardinal sins.

 

 In the first paragraph they make a huge mistake in kinetic energy application : kinetic energy applied in the collision (0.5 * combined weight * relative speed^2), by introducing relative speed. by their logic if a tank going 60 km/h hits a tank going 40 km/h the whole kinetic energy is a square of 100 km/h, making collsision way too dangerous. This simplification of realtive speed also makes collision where one tank is backing away way too safe, for the same reason as before.

Also their simplification of combined weight increases energy for no reason when one of the tanks is stationary. 

 

Yes, I understand that this is simplification, but it just seems unnecessary.

 

 

But that IS how physics works. 

The relative speed is the only one that matters in an impact. 

I would say more, the formula they use is the actual formula of kinetic energy:

Ke= 1/2*m*(v^2)


Edited by Dava_117, 19 October 2019 - 02:41 PM.


Dr_Oolen #3 Posted 19 October 2019 - 02:40 PM

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So in real life when you ram a stationary tank you do 300 HP of damage instead of 400 if it was also moving?

Edited by Dr_Oolen, 19 October 2019 - 02:41 PM.


UserZer00 #4 Posted 19 October 2019 - 02:55 PM

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Plus the added factor "R" to ensure that Russian tanks deal more damage when ramming and receive less damage when being rammed....

8126Jakobsson #5 Posted 19 October 2019 - 02:55 PM

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Wargaming physics counts for bravery and style. Like this madlad that didn't lose a single point of hp.   :B



Balc0ra #6 Posted 19 October 2019 - 02:56 PM

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View Postmurn123, on 19 October 2019 - 02:35 PM, said:

Yes, I understand that this is simplification, but it just seems unnecessary.

 

And that's why. It's an arcade game aimed at everyone to be simple. Not just Neil deGrasse Tyson.

 

Then again as they also said. it's not just the speed or who is moving or not and the weight. But the armor thickness on the impact point of both. It's why the 50B is a good rammer, as the armor at the point of impact is the thickest.



murn123 #7 Posted 19 October 2019 - 02:59 PM

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View PostBalc0ra, on 19 October 2019 - 01:56 PM, said:

 

And that's why. It's an arcade game aimed at everyone to be simple. Not just Neil deGrasse Tyson.

 

Then again as they also said. it's not just the speed or who is moving or not and the weight. But the armor thickness on the impact point of both. It's why the 50B is a good rammer, as the armor at the point of impact is the thickest.

I dont have a problem with that part. Just the way they come to how much energy there actually is is wrong.



XxKuzkina_MatxX #8 Posted 19 October 2019 - 03:00 PM

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View Post8126Jakobsson, on 19 October 2019 - 05:55 PM, said:

Wargaming physics counts for bravery and style. Like this madlad that didn't lose a single point of hp.   :B

 

Like it is not enough driving this thing but he wanted style points too. Cheeky so and so! :angry:



murn123 #9 Posted 19 October 2019 - 03:09 PM

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View PostDava_117, on 19 October 2019 - 01:40 PM, said:

 

But that IS how physics works. 

The relative speed is the only one that matters in an impact. 

I would say more, the formula they use is the actual formula of kinetic energy:

Ke= 1/2*m*(v^2)

Kinetic energy of 2 tanks with the same speed v and mass m in a head on collision is 2*(0.5*m*v^2), and not as wargaming logic says (0.5*2m*(2v)^2). That is a mistake by a factor of 4.



Dava_117 #10 Posted 19 October 2019 - 03:26 PM

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View Postmurn123, on 19 October 2019 - 03:09 PM, said:

Kinetic energy of 2 tanks with the same speed v and mass m in a head on collision is 2*(0.5*m*v^2), and not as wargaming logic says (0.5*2m*(2v)^2). That is a mistake by a factor of 4.

 

Well, that is not much related to the relative speed tho. The approximation is that, for an inelastic collision, you have an effective mass mr=(m1*m2)/(m1+m2) and not just the mass sum.


Edited by Dava_117, 19 October 2019 - 03:26 PM.


murn123 #11 Posted 19 October 2019 - 03:51 PM

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View PostDava_117, on 19 October 2019 - 02:26 PM, said:

 

Well, that is not much related to the relative speed tho. The approximation is that, for an inelastic collision, you have an effective mass mr=(m1*m2)/(m1+m2) and not just the mass sum.

I assumed that by relative speed they simply ment V=v1-v2 in vector space. Ofcourse here we are talking about the inelastic collision, the formulas for which are very clear and understood. The problem i am having is that what wargaming did is obviously a simplification (nothing wrong with doing them), which is clearly very wrong ( unless their formula for relative speed is something very different, but i don't think it is). Imo a better simplification would be to just assume that speed after head on collision is zero and assume that all inital kinetic energy is transferred to explosion. There would be less of an error. (factor of 4 seem more like a mistake than simplification).


Edited by murn123, 19 October 2019 - 03:57 PM.


shikaka9 #12 Posted 19 October 2019 - 04:00 PM

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WG physics isnt Earth based

Dava_117 #13 Posted 19 October 2019 - 04:55 PM

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View Postmurn123, on 19 October 2019 - 03:51 PM, said:

I assumed that by relative speed they simply ment V=v1-v2 in vector space. Ofcourse here we are talking about the inelastic collision, the formulas for which are very clear and understood. The problem i am having is that what wargaming did is obviously a simplification (nothing wrong with doing them), which is clearly very wrong ( unless their formula for relative speed is something very different, but i don't think it is). Imo a better simplification would be to just assume that speed after head on collision is zero and assume that all inital kinetic energy is transferred to explosion. There would be less of an error. (factor of 4 seem more like a mistake than simplification).

 

Well, guess they took into account the fact that the final speed won't be zero. In fact, we already have tanks being pushed by a strong impact. 



Negativvv #14 Posted 19 October 2019 - 05:14 PM

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Still better than soap stone physics when trying to drive up hill....



murn123 #15 Posted 19 October 2019 - 05:43 PM

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View PostDava_117, on 19 October 2019 - 03:55 PM, said:

 

Well, guess they took into account the fact that the final speed won't be zero. In fact, we already have tanks being pushed by a strong impact. 

Maybe the whole confusion comes from combined mass. Sorry i did not quite understand your first replay, you probably ment to say that combined weight is actually effective mass. and my assumption of relative speed was correct. Then the formula would make sense. When i read combined weight i immediatly assumed they ment sum mass of both vehicles, which would be wrong (or a very weird approximation, since this than leads to the discrepency that i shoved with 2 identical objects in head on collision). Obviously loss in kinetic energy for inelastic collision is =0.5*(m1*m2/(m1+m2))*(v1-v2)^2.

 

 


Edited by murn123, 19 October 2019 - 05:52 PM.


malachi6 #16 Posted 19 October 2019 - 05:58 PM

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Watch the episode of Mythbusters where they explain you do not add the velocities of moving vehicles together and the effect is demonstrated.

 

Can't find the episode but here is a blog about it.

 

http://gregladen.com/blog/2017/10/11/mythbusters-on-head-on-collisions/


Edited by malachi6, 19 October 2019 - 06:01 PM.


Dava_117 #17 Posted 19 October 2019 - 07:11 PM

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View Postmurn123, on 19 October 2019 - 05:43 PM, said:

Maybe the whole confusion comes from combined mass. Sorry i did not quite understand your first replay, you probably ment to say that combined weight is actually effective mass. and my assumption of relative speed was correct. Then the formula would make sense. When i read combined weight i immediatly assumed they ment sum mass of both vehicles, which would be wrong (or a very weird approximation, since this than leads to the discrepency that i shoved with 2 identical objects in head on collision). Obviously loss in kinetic energy for inelastic collision is =0.5*(m1*m2/(m1+m2))*(v1-v2)^2.

 

 

 

Yeh, its quite weird to use combined mass as can be both the weighted mass as the direct sum. 

It may also be that the simple sum of the mass was taken as balancing factor to bring impact damage in line with the HP pool. In this way they kept the dependency on both tank mass but with a damage output in the right range. :)


Edited by Dava_117, 19 October 2019 - 07:12 PM.


Baldrickk #18 Posted 19 October 2019 - 07:30 PM

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View Postmalachi6, on 19 October 2019 - 05:58 PM, said:

Watch the episode of Mythbusters where they explain you do not add the velocities of moving vehicles together and the effect is demonstrated.

 

Can't find the episode but here is a blog about it.

 

http://gregladen.com/blog/2017/10/11/mythbusters-on-head-on-collisions/

Yeah,  I didn't have this link but was going to say the same thing. 

Two identical objects hitting each other in a collision is no different than one striking a solid, immovable object.

There's twice as much energy with two,  but also twice the mass. 

 

When the mass isn't equal though,  that's when the fun happens. 



Mr_Burrows #19 Posted 19 October 2019 - 07:53 PM

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View Post8126Jakobsson, on 19 October 2019 - 02:55 PM, said:

 

 

Wargaming physics counts for bravery and style. Like this madlad that didn't lose a single point of hp.   :B

 

Dang, I need to go back n play some low tiers to get to Province The weather at Erlenberg is just so dull and gloomy. 



RamRaid90 #20 Posted 20 October 2019 - 10:59 AM

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It's a game.  :great:




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