How hard do you have to smash into a car windscreen for it to break?

well, i've broken windshields with one swing of a sledgehammer, so that should do it.

thats a good few newton. I've smashed marble rocks with one swing of a sledgehammer.

Well, my friend got hit by a car and smashed the windscreen with his head. He was fine so I doubt it has to be very hard ^_^

I heard somewhere(I think it was TV) if you punched a windscreen hard enough to break it you would undoubtadly break your wrist possibly lots of other things.

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Original post by normal31337guy I heard somewhere(I think it was TV) if you punched a windscreen hard enough to break it you would undoubtadly break your wrist possibly lots of other things.

I punched a fence and broke my wrist.. The fence wasn't even strong. I'm guessing the windscreen would really hurt...

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Original post by normal31337guy I heard somewhere(I think it was TV) if you punched a windscreen hard enough to break it you would undoubtadly break your wrist possibly lots of other things.

I saw a guy on RealTV making a home movie punch through a windshield, he jumped on the hood of the car and punched it real hard, it kinda spider-webbed so he punched it a few more times until his hand went through. When he was done his arm was all cut up and I imagine he broke some bones in his hand too. He was a big guy too, if I remember right.

I've always enjoyed the "britishism" that is "windscreen".

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Original post by TANSTAAFL I've always enjoyed the "britishism" that is "windscreen".

Me too. Its is funnay.

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Original post by pkelly83 I was just pondering this as I got smashed by a Taxi crossing the road in Waterford yesterday evening. The wind (screen) (shield) was samshed to bit, and I was standing up walkingh around minutes after it happend, I'm just wondering what kind of force you need to smash safety glass?

Safty glass is one sheet of pastic sandwiched between two sheets of glass. Punching through the glass requires not only to break the glass but to bend the plastic enough so it also breaks.

Not easy.

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I'm just wondering what kind of force you need to smash safety glass?

From Jesse Wilcox, customer-service representative of Safelite Auto Glass:

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Our average safety glass withstands about 1,800 N of instantaneous force when stressed orthogonally (through the windshield's central axis) before cracking begins to appear. An instantaneous force of about 2,000 N or higher would probably crack the windshield significantly, and anything above 2,100 N would almost certainly cause it to shatter completely.

As a matter of fact, I find "wind shield" hilarious :)

Windscreen, like sunscreen, but for high protection against the erosive qualities of the wind ;-)

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Original post by Binomine Quote: Original post by pkelly83 I was just pondering this as I got smashed by a Taxi crossing the road in Waterford yesterday evening. The wind (screen) (shield) was samshed to bit, and I was standing up walkingh around minutes after it happend, I'm just wondering what kind of force you need to smash safety glass? Safty glass is one sheet of pastic sandwiched between two sheets of glass. Punching through the glass requires not only to break the glass but to bend the plastic enough so it also breaks. Not easy.

Wow, I've never really thought about it. But just before I read your post I was wondering how they did that, I'd just assumed a think peice of glass, maybe with metal in it. But damn! What an ingenious solution.

You should carry a few dead batteries or small pebbles for this occasion, it hurts less than using your head.

You could also keyscratch the bonnet, or when arguing with the driver about him jumping the lights, keyscratch his door. With the latter, he won't see it until he gets home, then its too late to complain.

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Original post by kSquared Quote: I'm just wondering what kind of force you need to smash safety glass? From Jesse Wilcox, customer-service representative of Safelite Auto Glass: Quote: Our average safety glass withstands about 1,800 N of instantaneous force when stressed orthogonally (through the windshield's central axis) before cracking begins to appear. An instantaneous force of about 2,000 N or higher would probably crack the windshield significantly, and anything above 2,100 N would almost certainly cause it to shatter completely.

In other words, if your arm weighed 10 pounds (4,500 kg), you would have to punch with an acceleration of ~ 1/2 a meter/second^2 in order to get your hand through and break the windsheild. I guess if you jumped off an incline and got some acceleration due to gravity and went through hand first you can do it.

I seem to remember that most fatalities due to human-automobile collision, even if they end up on the windshield, are NOT forceful enough to smash the glass.

So even if you died in the impact, it would only cause enough force to make it spider. Assuming you're about 200lb (~100kg) you'd have to be accelerating really fast to smash the glass (F = ma; 2100/100 = 21m/s^2 acceleration towards the windshield).

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if your arm weighed 10 pounds (4,500 kg),

hehehahahea, just imagined 4500 kg arm.

Actually 4.5kg body part need to have acceration 2000/4.5 = 444 m/s², that is, 45G.

and 21m/s^2 it's roundly 2.1G....

it is not rigid, so the problem....

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Original post by Dmytry Quote: if your arm weighed 10 pounds (4,500 kg), hehehahahea, just imagined 4500 kg arm. Actually 4.5kg body part need to have acceration 2000/4.5 = 444 m/s2, that is, 45G. and 21m/s^2 it's roundly 2.1G.... it is not rigid, so the problem....

Keep in mind that those numbers were only for an orthogonal force. A lateral force of much lower magnitude would crack or shatter the windshield easily.

speaking of which.... http://www.i-gear.net/death/

Well it was a Taxi that hit him (dirty taxi drivers) so lucky those money grabbing b4stards are not trying to get money off him for time the car is off the road etc.

Get better soon mate! You must have a thick skull!