(May 6, 2013 at 2:09 pm)pocaracas Wrote: The comparison was with a wall, not another car.

Yes, I know, that's why it doesn't compare well with the situation at hand. A head-on collision between two vehicles each going 50 does more damage than if the same vehicles are doing 50 and 10 respectively.

(May 6, 2013 at 12:58 am)FallentoReason Wrote:

Quote: At a combined impact velocity of a hundred miles per hour

Opposing velocity vectors aren't additive like that.

I didn't suggest that the force or energy was. My intent was to illustrate that at highway speeds, mistakes leave little margin for reaction. I worded it poorly. Mea culpa, I was pretty upset at the time.

I have no doubt that the outcome would have been identical had the motorcyclist and his passenger been stationary and struck by a car traveling at 50mph rather than traveling in opposite directions at 50mph.

---

As is often the case with stories like this, it appears that the report of a third person evacuated by helicopter are not true, according to new reports. The driver of the SUV had only minor injuries.

http://www.komonews.com/news/local/Fatal...17841.html

When I first moved out here I was of course accustomed to NY drivers who I thought were the worst on earth. However, shortly after there was one of those "fog in the mountains" episodes in California and they were interviewing a cop who said...with a completely straight face...." we had 120 accidents in the last 24 hour period...which is about 3 times more than normal."

I'm listening to this thinking....40 is NORMAL!!!!

I don't know if AZ drivers suck or not. One factor is the sun which is always in your eyes during rush hour.

Where I am we have a lot of 90 year olds driving big ole fucking Buicks or Lincolns and these dementia-riddled fucks should be dragged out of their cars and locked up in an Alzheimer's ward for everyone's safety.

(May 6, 2013 at 2:16 pm)John V Wrote:

(May 6, 2013 at 2:09 pm)pocaracas Wrote: The comparison was with a wall, not another car.

Yes, I know, that's why it doesn't compare well with the situation at hand. A head-on collision between two vehicles each going 50 does more damage than if the same vehicles are doing 50 and 10 respectively.

Eh, once again, the comparison was with a sturdy wall, not a car travelling at 10. If you're trying to argue against the physics, you won't win. You're thinking about momentum whereas the discussion is about velocity.

(May 6, 2013 at 3:12 pm)mo66 Wrote:

(May 6, 2013 at 2:16 pm)John V Wrote: Yes, I know, that's why it doesn't compare well with the situation at hand. A head-on collision between two vehicles each going 50 does more damage than if the same vehicles are doing 50 and 10 respectively.

Eh, once again, the comparison was with a sturdy wall, not a car travelling at 10. If you're trying to argue against the physics, you won't win. You're thinking about momentum whereas the discussion is about velocity.

On the other hand, this case in particular had a car going against a bike.
A car weighs about 1000kg... a bike, a mere 200kg.
If the speeds were comparable, we still have a net momentum in the direction of the car.... of about 4/5 of the car's speed.

(May 6, 2013 at 3:24 pm)pocaracas Wrote:

(May 6, 2013 at 3:12 pm)mo66 Wrote: Eh, once again, the comparison was with a sturdy wall, not a car travelling at 10. If you're trying to argue against the physics, you won't win. You're thinking about momentum whereas the discussion is about velocity.

On the other hand, this case in particular had a car going against a bike.
A car weighs about 1000kg... a bike, a mere 200kg.
If the speeds were comparable, we still have a net momentum in the direction of the car.... of about 4/5 of the car's speed.

But the phrase the OP used is still false, there's no "combined" velocity of 100, you can't add velocities like that, adding together the initial velocities will not get you the final velocity (and yes, it is in the direction of the car as you kindly pointed out).

(May 6, 2013 at 3:28 pm)mo66 Wrote: But the phrase the OP used is still false, there's no "combined" velocity of 100, you can't add velocities like that, adding together the initial velocities will not get you the final velocity (and yes, it is in the direction of the car as you kindly pointed out).

You're missing the forest for all the trees. What is the velocity of the car relative to the motorcycle and vice versa?

This isn't a goddamned physics thread, you know. It's a fucking rant. Go debate your fucking pedantry elsewhere.

(May 6, 2013 at 3:12 pm)mo66 Wrote: Eh, once again, the comparison was with a sturdy wall, not a car travelling at 10.

Once again, the actual case at hand involves two vehicles.

Quote:If you're trying to argue against the physics, you won't win. You're thinking about momentum whereas the discussion is about velocity.

I'm thinking of energy, as I said. In this case kinetic energy, which is proportional to square of velocity. I agree with FtR's statement that you can't simply add velocities. A crash between two vehicles going 30 would have different results from the same two vehicles crashing at 10 and 50, even though both cases sum to 60.

However, his comparison to the brick wall is faulty.

Well.... regardless of what we can compare the actual situation to... the reality is that the guy in the bike died, while the guy in the SUV only had minor bruises... probably due to the seat belt. -.-'
Last I heard, that was enough to file charges of manslaughter.

(May 6, 2013 at 3:43 pm)John V Wrote:

(May 6, 2013 at 3:12 pm)mo66 Wrote: Eh, once again, the comparison was with a sturdy wall, not a car travelling at 10.

Once again, the actual case at hand involves two vehicles.

Quote:If you're trying to argue against the physics, you won't win. You're thinking about momentum whereas the discussion is about velocity.

I'm thinking of energy, as I said. In this case kinetic energy, which is proportional to square of velocity. I agree with FtR's statement that you can't simply add velocities. A crash between two vehicles going 30 would have different results from the same two vehicles crashing at 10 and 50, even though both cases sum to 60.

However, his comparison to the brick wall is faulty.

It isn't faulty no, I can guarantee that. But in any case, whatever the speed was, somebody died from it, and I'm pretty sure they're not thinking about what speed they were travelling at when they died. I think the overriding lesson to be learnt here is that we will all die someday and all our bickering about velocity and energy will be totally meaningless and irrelevant (except for the 15yr old physics geek accessing this forum on the planet Mars 250 years from now).