I saw a television show about automobile accidents. In the one scenario, an accident victim, using a dash cam, actually filmed what could have easily been her own death.

She was traveling on a highway. There is a truck in front of her traveling in the same direction and about the same speed. The truck was carrying lumber and lost a board off the load. The board stuck the victims windshield at what they said was 90 miles an hour.

How could this be possible? If both vehicles were traveling in the same direction and at the same speed, wouldn't the board appear to drop straight down as in relation to the victim? At worst it might strike the victim's vehicle at 10-20 MPH assuming she was passing.

Unless I misunderstood the scenario and they were actually traveling in different directions then I could easily see the 90 MPH estimate.

This is impossible. Even if the board were to slow 50% of it's velocity by catching the air and even if both vehicles were traveling at the unlikely speed of 120 mph...the board would impact the windshield at 60 mph.

It is more likely the vehicles were on either side of the road.

Split Infinity

 

Did you bother to read the thread there Splitty?

 

90mph or not, that board was hauling some serious @ss when it went through the windshield.

Only relative to the car. Relative to the ground I doubt it was moving much at all. The best description is that she hit the board while going something around 60mph (or faster). That's a serious impact speed. Recall some time when you accidentally walked into something, perhaps a wall in the dark. It probably really hurt and that was only about 3mph. Try running as fast as you can toward a brick wall and throwing your arms out stop you at the last moment. That would only be about 10mph or slightly more. I did that in fifth grade when someone opened a steel fire door just as I got there. It knocked me senseless for several minutes (and some would say I have yet to fully recover).

 

Try running as fast as you can toward a brick wall and throwing your arms out stop you at the last moment. That would only be about 10mph or slightly more. I did that in fifth grade when someone opened a steel fire door just as I got there. It knocked me senseless for several minutes (and some would say I have yet to fully recover).

Heh. I did that, except with glass double doors. I was running, my right hand pushed the right side door open while my face went through the left side glass. There was alcohol involved, obviously.

 

Did you bother to read the thread there Splitty?

Yeah...my bad.

Split Infinity

 

It also looks like she may have hit the bottom of the board while moving forward, flipping it in an arc toward the window. That would also transfer some speed to the lumber. My physics skills are not my strong suit, so I cannot analyze how much speed.

 

It also looks like she may have hit the bottom of the board while moving forward, flipping it in an arc toward the window. That would also transfer some speed to the lumber. My mechanical engineering skills are non-existent, so I cannot analyze how much speed.

Now that you mention it, the board does appear to flip when it hits the front left of the vehicle. Trying to calculate that out would be a bit hairy, since you'd need to find the center of balance on the board, and where on the board the vehicle impacted to impart the spin. The extra bump prior to the windshield does explain how it comes in at an odd angle, the board appears to have been nearly parallel with the car prior to the impact, at which point it became nearly perpendicular.

 

Which goes back to the elastic rebound I was talking about. A ball, bouncing off the floor, transfers a lot of its energy into an equal but opposite vector.

 

It was only a month ago when my left front tire flipped a chunk of two by four up. After it bounced off the floor pan, it ripped a chunk out of the right rear tire (sidewall injury). That sucker was flat in 2 seconds. As a matter of luck, I phoned a friend and he knows the guy that runs the AAA tow truck at night. I was home and safe in 35 minutes!

All luck, some bad, some good.

 

You can see the board coming from the left side of the trailer. It looks to me like the board was sucked into the vacuum created by the trailer and was travelling at a significant speed in relation to the road sign.

 

Clearly the photographer is pointing the video camera towards that vehicle from the start. That seems a bit strange to me. Staged?

 

Clearly the photographer is pointing the video camera towards that vehicle from the start. That seems a bit strange to me. Staged?

But if you watch closely, the board doesn't come from the vehicle being taped.

 

But if you watch closely, the board doesn't come from the vehicle being taped.

You're right. After looking frame by frame the board certainly appears to be setting on left side of the road, and the vehicle on the left kicked it up. So it was probably mostly a vertical trajectory and the car hit the board near road speed.

Scary.

 

My 2 cents...
Although posts on this are old...
I agree with #12
The board was laying on the side of the road....at least thats what it looks like to me...
The Car pulling the trailer might have missed it due to the narrower width of the car's (or truck's )wheelbase.
But...the trailers wheel struck the board on it end and popped it up in the air....
she hit the board doing 60 ...or whatever....
Ive had it happen to me....but the board didnt come inside my car....
just my 2 cents.