…can the heat cause the window(s) to blow out? It’s just about to start raining here so there’s a mass exodus of people going outside to close the windows on their cars. Everyone seems to be in agreeance that the reason they do it is because if it gets hot enough the windows can be blown out.
On it’s face it sounds a bit silly, but heated air will expand, so what say we? I’ve never heard of such a thing before right now.
The cabin of a car is hardly air tight. If it was, people would suffocate on long car rides. Also, the amount of expansion from, say, 20 C to 40 C isn’t very much. In absolute temperatures, that’s 293 K to 313 K. That would cause less than a 1% increase in pressure given constant volume.
The real reason is to keep the car cooler by letting the hot air escape.
I assume you’re saying this is the reason they leave the windows down in the first place (the obvious reason for their running out to close them being they don’t their cars wet inside).
Jillions of cars have been parked for jillions of hours with the windows up in hot temperatures without the windows being blown out. Furthermore, car windows are notorious for their strength. Special tools are made to break them to allow exiting a submerged car, because even strong people can’t kick them into breaking. That notion that air pressure could break them doesn’t have any evidence to support it.
What can happen sometimes is that car window glass will spontaneously shatter. It’s rare, but not unheard of. It happened on one of my cars, and it was parked with the windows shut on a hot day. There’s no way it blew out - it was an old convertible that leaked (air) like a sieve. And interestingly, most of the broken glass was on the inside of the car.
No, though at first I thought maybe a ball or rock had done it. The car was in my driveway, I was in the house and heard a loud pop/glass breaking noise. I went right out and saw the broken window. No one else was around, some of the glass was inside the car and some was outside, and I never found any object inside the car that might have caused it. In talking to the glass company, I was informed that this type of spontaneous breakage has been known to occur.