New truck #@$%@#&

[Industrial Toys]

I would have said "combined speed". If you ever see the footage of aircraft striking a concrete barrier in time lapse, I would guess hitting an immovable object is worse than hitting a moving object given the same speed deferential.

 

[DieselBound]

It DEPENDS. Force = Mass x Acceleration

Deformation, or energy absorption, comes into play for figuring collision forces, but that's a bunch more math...

 

[dnw64]

50% more force coming at you than hitting a stationary object.

It depends. On a lot of factors.

Compared to hitting an immovable object, for the force to be greater, the other object has to be larger and/or moving faster than you AND have a fairly rigid form factor. Just as an example, if you're driving your 2018 aluminum body F150 at 100 mph and hit a tumbleweed traveling in the opposite direction, also at 100 mph not much will happen. Or, say that instead of a tumbleweed, pretend that someone invented a 5000# marshmellow that somehow got to 100 mph. That's taking it to extremes, but doing so proves the point. It's not just speed, it's also mass and form. And that's why hitting an almost unmovable object (such as a bridge abutment) is going to generally have the same effect as hitting a similar vehicle at the same speed coming from the opposite direction.

 

[buckeyefarmer]

It depends. On a lot of factors.

Compared to hitting an immovable object, for the force to be greater, the other object has to be larger and/or moving faster than you AND have a fairly rigid form factor. Just as an example, if you're driving your 2018 aluminum body F150 at 100 mph and hit a tumbleweed traveling in the opposite direction, also at 100 mph not much will happen. Or, say that instead of a tumbleweed, pretend that someone invented a 5000# marshmellow that somehow got to 100 mph. That's taking it to extremes, but doing so proves the point. It's not just speed, it's also mass and form. And that's why hitting an almost unmovable object (such as a bridge abutment) is going to generally have the same effect as hitting a similar vehicle at the same speed coming from the opposite direction.

The scenario i responded to was 2 vehicles coming at each other.

 

[dnw64]

The scenario i responded to was 2 vehicles coming at each other.

Right. Which is about the same as hitting a "brick wall" if they are of similar mass and speed.

 

[aczlan]

What does "closing speed" mean? And how does it have any real life application? IOW, how do two vehicles (of equal mass) hitting each other head on at 100 mph differ from one vehicle traveling at 100 mph hitting a bridge abutment?

It doesn't, however in this case, a the truck was going about 100mph in one direction and the car was going at 50mph in the other direction. If they are similar mass (truck with 2 people and nothing into he bed vs car with 2 people in it), that is like the truck hitting a parked car at 150mph.
It would differ from a bridge abutment in that the car has a crumple zone that will absorb some of the force and the truck going faster will mean that it has more force to contribute to the equation and it will probably push the car backwards.

Aaron Z

 

[CADplans]

Each vehicle adds force to the collision,,, assume similar weight and the weight (M) is 1000 (units does not matter,,)
V1 is 50
V2 is 100
F=1/2 M(Vsquared)

F1 = 1/2 1000 ( 2500 ) = 1,250,000
f2 = 1/2 1000 (10,000) = 5,000,000

Force total is = 6,250,000

The truck adds 80% of the force,, the 50MPH car adds 20% of the force,,,

The best way to increase force is to double the velocity, rather than double the weight,,,
That squaring of the velocity really ups the ante of the truck,,,

Now, how that force is dissipated,, that is a different subject,,,

A truck hitting a bridge at 150 velocity would be
F3 = 1/2 1000 (22,500) = 11,250,000
That is almost double the energy of the two vehicles colliding,,,

 

[dnw64]

It doesn't, however in this case, a the truck was going about 100mph in one direction and the car was going at 50mph in the other direction. If they are similar mass (truck with 2 people and nothing into he bed vs car with 2 people in it), that is like the truck hitting a parked car at 150mph.
It would differ from a bridge abutment in that the car has a crumple zone that will absorb some of the force and the truck going faster will mean that it has more force to contribute to the equation and it will probably push the car backwards.

Aaron Z

Correct.

 

[Industrial Toys]

I bet that tumble weed would do thousands of dollars, front end damage on most trucks today. Probably some would be written off completely,

 

[dnw64]

I bet that tumble weed would do thousands of dollars, front end damage on most trucks today. Probably some would be written off completely,

Of course. But I bet the seatbelt locks wouldn't engage and that you'd be able to drive the truck home.