Incorrect Physics in Call of Cthulhu!

[The Allamistako]

AAAAAAAAAAAAAAAAARRRRRRRRRRRRRRRRRRRRRRRRRGGGGGGGGGGGGGGGGGGGGGGGGGHHHHHHHHHHHHHHHHHHHHHHHHHH!

"I think my brain hurts!"



-Alla

 

[Blacksad]

AAAAAAAAAAAAAAAAARRRRRRRRRRRRRRRRRRRRRRRRRGGGGGGGGGGGGGGGGGGGGGGGGGHHHHHHHHHHHHHHHHHHHHHHHHHH!

"I think my brain hurts!"



-Alla

Wanna play a 3D space combat in Jovian Chronicles using the silhouette Game System with me as a GM, currently none of my player agreed to do that, I'm still wondering why

 

[Bagpuss]

I haven't missed it, but it's inaccurate.

let say you go from 200m/s to 50m/s in 1s, it's effectivly a 150m/s*s acceleration, and you continue to go forward.

let say you go from 50m/s to -50m/s in 1s, it's effectivly a 100m/s*s acceleration, and you go backward.

the first acceleration is the worst to the human body. the link you gave say the opposite. also it use a wall as the innert object and not a car of similar mass in the example, so it tends to modify the results.

m1*v1 + m2*v2 = m3*v3
but since the masses stick together, and the cars are the same mass
m1 = m2
m3 = 2*m1
m1*v1 + m1*v2 = 2*m1*v3
so, v3 = (v1 + v2)/2


But your example is inaccurate as well since if you subsitute your values in the equation (thanks Zerovoid) then

v3 = (200-50)/2
v3= +150/2
v3= +75 ms

So car 1 goes from 200 to 75 m/s a acceleration of 125m/s*s
and car 2 goes from -50 to +75 m/s also an acceleration of 125 m/s*s so it doesn't make what difference the speeds are assuming the cars are of equal mass.

Now if the car hits a brick wall and goes from 200 m/s to a dead stop in the same time (1 second) then the change then the deceleration is worse (200 m/s*s).

So either I've made a mistake or its better to hit an on comming vehicle than a brick wall. God its been so long since I've done physics.

 

[Castellan]

I haven't missed it, but it's inaccurate.

Nope.

Try another example. Let's say two cars heading in opposite directions strike the same building, clearly an immovable object. For each of them, the building absorbs the energy of the collision and imparts no net force on the cars whatsoever. We can't deny that.

Now, let's make the building skinnier and try again. Same result.

Make it skinnier still. Keep making the building skinnier until it's only an inch-thick wall. Both cars are still running into the wall (which, for our purposes here, we'll consider to have a tremendous mass -- perhaps it's made out of Plutonium or some such heavy element) and experiencing a collision with a solid object.

If we continue making the wall smaller and smaller until it's essentially non-existant, we have the cars running into each other. Each car acts as a "wall" for the other car, absorbing the other car's energy and imparting its own energy to the impactor. The net result is each car receives only the energy from the other car, not from itself as well. As was stated earlier, if both cars experienced all of the energy, you'd get twice as much energy out of the system as you put in. Clearly, you can't create energy (it's a fundamental law) so it must be conserved.

Presuming you could add the speeds together, and impart full damage to each vehicle, we wouldn't bother with inefficient fuel sources like coal, water, or nuclear. We'd figure out a way to harness the energy of crashing cars. Because, in the long run, we'd make more money that way!

 

[Blacksad]

m1*v1 + m2*v2 = m3*v3
but since the masses stick together, and the cars are the same mass
m1 = m2
m3 = 2*m1
m1*v1 + m1*v2 = 2*m1*v3
so, v3 = (v1 + v2)/2


But your example is inaccurate as well since if you subsitute your values in the equation (thanks Zerovoid) then

v3 = (200-50)/2
v3= +150/2
v3= +75 ms

So car 1 goes from 200 to 75 m/s a acceleration of 125m/s*s
and car 2 goes from -50 to +75 m/s also an acceleration of 125 m/s*s so it doesn't make what difference the speeds are assuming the cars are of equal mass.

Now if the car hits a brick wall and goes from 200 m/s to a dead stop in the same time (1 second) then the change then the deceleration is worse (200 m/s*s).

So either I've made a mistake or its better to hit an on comming vehicle than a brick wall. God its been so long since I've done physics.

The example that I have given aren't linked, that's the error, the examples you quoted were just to explain why the explanation given by the link

When you have a head-on collision with the slower car you will continue forward after impact; there will be some "give" in the collision. You'll decelerate to a gradual stop, which is certainly better than colliding against a massive wall with no give. On the other hand, when you collide with the high speed car the force of impact will be greater and you'll do worse than slowing down or coming to an abrupt stop — you'll be snapped into a sudden reverse direction with a "negative give."

is false, ie the greater the accelerartion, the worst for your body, that your car continue to go forward or not doesn't have anything to do with that.

and on acceleration, you are right, it is better to hit something that can move in your direction than in a wall, but the energy involved in a schock between 2 cars that go in opposite direction is greater than the energy of a schock between a portion of wall and a car, so the car will be more damaged, and the person inside too.

 

[CRGreathouse]

So either I've made a mistake or its better to hit an on comming vehicle than a brick wall. God its been so long since I've done physics.

I'm no physicist by a long stretch, but here's what I see in the equations: It's better to hit a car going more slowly than you are in the opposite direction than into a wall (200 -> 75: 125; 200 -> 0: 200), but worse to hit a faster car (-50 -> 75: 125; -50 -> 0: 50) than into a wall.

 

[Blacksad]

Nope.

Try another example. Let's say two cars heading in opposite directions strike the same building, clearly an immovable object. For each of them, the building absorbs the energy of the collision and imparts no net force on the cars whatsoever. We can't deny that.

I want a plutonium building for my birthday!

You have two cars with the same energy 2A that enter into each other, each car has to deal with 2A energy.

You have a car with energy 2A that hit a wall with energy 0, the car has to deal with A energy.
[edit]
the wall has to deal with A energy, but nobody will mourn the wall
[/edit]

the energy stay the same.

Clearer that way?

 

[Aaron L]

i like pie

 

[Ulrick]

What if both cars were made out of the stuff they make Nerf footballs?




Ulrick

 

[Blacksad]

What if both cars were made out of the stuff they make Nerf footballs?




Ulrick

They'll get the same amount of damage, but their very high DR will prevent them from getting damaged.
Very simple, isn't it