Calculating impact velocity of an accident

[Grenoble]

OK, I saw this in the "Show us your crash pics!!" thread (http://www.pistonheads.co.uk/gassing/topic.asp?h=0&f=23&t=877946&i=2340&mid=&nmt=)


http://www.dailymail.co.uk/news/article-2204373/Co...



Anyone good at physics and could reverse engineer the impact speed of the Lexus to the Audi to be able to launch that far?

[TinyCappo]

This the one from surrey.

Missed a corner
takes out a postbox (one of the big feck off round ones)
Goes through a fence
"mounts" an audi (why cant they say uses as launch ramp fking it in the process)
Then gets enough air to get to the first floor and through a brick wall

Got to be three figures when they left the road

[TheTurbonator]

If you look at the Daily Fail pictures, then there's one which shows the postbox and more importantly, two metal poles. They're the kind you use to stop people gaining access to a parking space or stop joyriders gaining access to a field. One has been totally flattened the other is still raised slightly.

In my opinion the Lexus has gained some air from that raised pole and flew in a corkscrew fashion towards the Audi. It has then been off the ground high enough for it to ride along the top of the Audi and gain even more air, instead of just hitting in square on.

Would agree that it has to be in triple figures. It's more amazing that no one in the car was seriously injured and there wasn't a fatality.

[Simpo Two]

The police have people who calculate that kind of thing, yes. Although skid marks are their favourite tool and this car was too high to have any!

[anonymous-user]

Kinetic Energy increases with the square of velocity. No way was that a 3 figure exit velocity.

Look at a crash test at 40mph for example.


Assuming the driver was a passenger from the moment the car hit the first post (launched off the ground, the G force would prevent any decceleration or control over the vehicles vector by the driver (and the wheels not touching the floor obviously!). A "solid brick wall" is nothing like solid, it would easily be possible to knock that hole (especially as it is high up the wall and relatively poorely supported (unlike down near the foundations )) at less than 20mph at a guess.

It's simple maths to estimate the required velocity to get the car from the launch point to the height at which it hit the wall. (although you will have to estimate the vertical acceleration which the car experienced as it launched up the post)

[AshVX220]

Simpo Two said:

The police have people who calculate that kind of thing, yes. Although skid marks are their favourite tool and this car was too high to have any!

I suspect the driver of the flying car may disagree with that.

Though I agree, any skid marks in attendance may not be suitable for calculating the cars velocity.

[SpeckledJim]

At three figures there's almost nothing recognisable left.

50-60 my guess.

[McSam]

Max_Torque said:

Kinetic Energy increases with the square of velocity. No way was that a 3 figure exit velocity.

Look at a crash test at 40mph for example.
...

This, and the rest of what you said.

If he hit the poles at 60mph, imagine how far that car's going to go. There's so much energy in it that impacts with most objects barely slow it, they simply deflect it - and as said above, you don't have to hit the wall very hard at all to do that. Bear in mind that as soon as he hits those metal poles, there's zero chance of slowing the car yourself, and any braking done between leaving the road and reaching the poles is minimal at best because of crap surfaces, an unsettled car and still trying to get round the corner. I'd be very surprised if you lost 20mph between the road and the poles.

[Simpo Two]

McSam said:

you don't have to hit the wall very hard at all to do that.

If you look closely it was mostly window, so even less energy needed.

[McSam]

Simpo Two said:

McSam said:

you don't have to hit the wall very hard at all to do that.

If you look closely it was mostly window, so even less energy needed.

Ah yeah - you can see the straight top line to the hole where the frame was. In that case it's little more than a final resting place!