venomballistics
Member
Punk and a pellet gun is my guess
Please explain this
- Thread starter oldman45
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DeathGrip
US Veteran
I heard the insects are fighting back against the dreaded windshield death by wearing little hardhats. You're lucky they didn't come clean through...........
Helmet laws suck.
At 70 mph, I would have overtaken a deflected rock. Good theory though. Doing 70 mph means 105 feet per second forward motion. While a rock thrown by a tire would be doing the same speed, once it hit the ground, the speed would decrease substantially. By the time it bounced up, the truck would have done been over it.
I actually considered hitting hummingbirds. There are a lot of them in the area but do they fly at night?
Probably little impact cracks in the windshield showing up out of nowhere.
A lady was doing about 80 according to witnesses but I have not put the pencil to it yet. She had a flat on the right rear about 100 miles west of there and her "donut" was installed for a spare. It was rated for 50 mph but she was well over that for an extended time. The tire gave way and shreaded. She lost control (unusual since most rear tires will not cause loss of control), crossed the median, crossed the west bound lane and rolled four times causing two passengers to be ejected. Both were badly injured but are expected to survive. Once I get the factory weight for the car, the amount of fuel in the tank and occupant weights, I will get closer on the speed.
DeathGrip
US Veteran
I heard the insects are fighting back against the dreaded windshield death by wearing little hardhats. You're lucky they didn't come clean through...........
Some days you're the bug,
Some days you're the windshield.
truckemup97
Member
The rock thrown forward from the top of a tire would be going considerably faster than the vehicle, would it not? The vehicle is doing 70, and the tire is rotating at the rate of once every six to eight feet, approximately.
That said, I can't remember that ever happening to me, and I've driven more than most folks...
There are many formulas that can be used but it boils down to the tire is moving at 70 mph or 105 feet per second. Anything coming off the tire will travel the same speed. All things inside the vehicle are travelling at the same speed. Changing speeds would cause the tire to turn at a different rate and therefore the objects thrown will travel at a similar rate. Now if you were to lose a wheel cover, it will travel the same mph but be rolling at a faster rate since it is smaller in circumference. This also why a baby riding in one's lap will fly forward with a stronger force in the event of an accident where the vehicle is suddenly stopped. The baby is an occupant that continues to travel at the speed of the vehicle until a force stops it or until natural deceleration takes place.
This is the type discussions we have at seminars, much like does a person get twice as wet or half as wet if they run in the rain.
nah, it was aliens disposing of an anal probe...
truckemup97
Member
You're the expert, of that I have no doubt. I'm not arguing with you, I'm just trying to understand. My physics classes were a long time ago and I've likely forgotten most of what I learned.
If I were standing in the back of the pickup and threw a rock, it would be going the speed of the pickup plus the speed of my arm at the time of release. Why would it be different if it were thrown (slung?) from the tread of a tire?
If I were standing in the back of the pickup and threw a rock, it would be going the speed of the pickup plus the speed of my arm at the time of release. Why would it be different if it were thrown (slung?) from the tread of a tire?
handejector
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Y'all are leaving out centrifugal force.
I think rotational speed of the tire also comes into play, compounded somehow with the truck's speed, but I'm not learned enough to know how.
Let's face it though- if the rock was not moving faster than the truck, how did it get ahead of the truck?
I think rotational speed of the tire also comes into play, compounded somehow with the truck's speed, but I'm not learned enough to know how.
Let's face it though- if the rock was not moving faster than the truck, how did it get ahead of the truck?
truckemup97
Member
Y'all are leaving out centrifugal force.
I think rotational speed of the tire also comes into play, compounded somehow with the truck's speed, but I'm not learned enough to know how.
Let's face it though- if the rock was not moving faster than the truck, how did it get ahead of the truck?
That's what I was trying to say. How is it that a gorilla can communicate more effectively than I?
amazingflapjack
US Veteran
How about a temp or pressure change. Was the A/C on? If it is more of a crack, I would look for something like that, or frame flex, or a combination of factors. Just tryin' to think outside the box. Flapjack.
No it would not. Your throw would have to be with such power that the rock speed would exceed the speed of the truck. A good ball pitcher can hit those speeds. Also you have drag on the rock from the wind. If you were inside the vehicle and it be possible to throw the rock, then the wind drag would not be as great.
Propulsion motion is constant. A rock slung from a tire is in constant motion with the tire. Then there is a force pushing it to a point of release but the force dies off with gravity. The same with a bullet. Unfired in a gun pointed the same way as the pickup motion, the bullet is travelling at the same speed as the truck. Given the ignition of the powder to propel the bullet, the bullet will exceed the speed of the truck but slow down with distance whereas the truck speed will remain constant.
Centrifugal force will initially propel an object at a higher rate of speed but it will bleed off speed rapidly once released from the powering force.
Now back to schools, I graduated with my engineering degree in 1967 or over 44 years ago. The mind dims with age.
There is an actual peck in the cracks. Something hit the windshield twice. What the something is will likely remain a mystery.
Gasman1972
Member
If you held a rock in your hand in the back of a truck at 60 mph, you and the rock would be going 60 mph. The moment you let go of the rock it instantly slows down because it has no driving force, just weight and gravity. If you throw it 30 mph the speed of the rock does not become 90 mph, it becomes 30 mph from the point you throw it. To a person standing on the road the rock would be going 90mph or a little less, but the rock and the truck zero out kind of, and at the moment you let the rock go the rock is going 30 and the truck is going 60.
The rock did not get in front of the truck. If we assume the rock was thrown from the tire treads as the rock was being brought down on the front side of the tire, then it would have hit the pavement, bounced up and while it is in a directional variance, it is slowing down while vehicle speed is constant. More than likely, a rock would have came loose to the rear and not to the front. Tread distortion happens when the tread is around the bottom of the tire. Rock dings are common to the rear of an inter fender, not the front.
Y'all are leaving out centrifugal force.
I think rotational speed of the tire also comes into play, compounded somehow with the truck's speed, but I'm not learned enough to know how.
Let's face it though- if the rock was not moving faster than the truck, how did it get ahead of the truck?
Lee, how many times have you had a rock hit your windshield that was thrown by your own tires? It would have to go down to the pavement, then upward far and fast enough out in front of the truck to gain enough altitude to hit the windshield
and that is not going to happen. The vehicle would have ran over it. You hear this all the time when a rock lets go from tire treads. The rock hits the undercarriage.
Have you ever seen a rock being thrown to the front of a vehicle?
I'm not a Mathematician, but I did stay at Holiday inn Express recently.
I don't buy your theory of the rock being thrown at same speed as vehicle speed.
Wheels/tires spin on spindle or axle and are measured by revolutions per minute.
The smaller the tire's diameter, the faster it will spin.
Say a vehicle is pulling a trailer behind it with little, tiny, wheels on it. These tiny wheels could potentially be spinning twice the speed of your tow vehicle's tires.
Both the car and trailer are doing 70 MPH - your theory says that rocks thrown from either tire will travel at same speed........NOT!
Also, I've been telling my wife for 30 years to quit following (tailgating) Big Trucks so close because they throw rocks BEHIND them (into her windshield) - I've never seen a tire throw a rock forward.
Finally, I'm sticking to my Bigfoot/Slingshot previous answer.
