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View Full Version : What's the pressure force of a falling beer can based on certain variables?



*Laurelindo*
08-26-2011, 12:10 PM
I felt like trying to calculate how much pressure a beer can would exert on, for example, a glass table, if it was dropped from a certain height, and if it had a certain weight and bottom area.
I figured that I should be able to do it like this:

p = F/A
F = (mv)/t
v = (2gh)^0,5
t = d v

p = md At2

...and solving t gives this:

t = (2h g)^0,5

This gave me the following equation:

p = md A*(2h/g)

So for example if the beer can had a weight of 1,0 kg and a bottom area of 0,40 dm<SUBP>2</SUP> then this would mean it had a pressure of 1,228 kPa, or 0,19 psi.
Could this be correct?

Mirage
08-26-2011, 02:38 PM
Part of the homework assignment is to figure it out on your own!

*Laurelindo*
08-26-2011, 07:34 PM
Part of the homework assignment is to figure it out on your own!This is no homework assignment, in fact schools usually start around the end of August in Sweden so I wouldn't have been able to get any important homework already by now anyway.
It's just some random stuff I drew and wrote on paper, and I was wondering if this was a correct way to think.
I have even posted a few questions just like this one on this forum a few months ago, why would I ask for help with "homework assignments" in the middle of a Summer vacation?
This is another similar type of question, and even if it really were homework it would still just be asking for confirmation of one's own thoughts and calculations = trying to figure things out oneself.

There's a difference between writing off an answer sheet and asking if one's thoughts are correct.


Part of the homework assignment is to figure it out on your own!With this logic you might as well say that physics is about figuring out the laws of nature on your own, and that reading physics books is cheating;
millions of physics students ask exactly the same kinds of questions like mine to their teachers all the time.
Seriously, I'm not handing out an entire homework assignment for you to answer - THAT would've been cheating.
I'm just asking if I have done correct calculations on something that isn't even homework, and if anything that should be considered a way of learning and understanding things.

And if people are gonna start obsessing over this now instead (which I hope they won't) then could they at least add a reply to my original, actual question, please?
It's really tedious when people start talking about something completely irrelevant and forget the original topic question.
No, it's not homework, yes, it's a random question with personal calculations and attempts to make it correct.
Some people just enjoy physics for its own sake, you know.

Victorsson
08-29-2011, 01:24 PM
Looks right to me, don't take my word for it though, it's been a few years since I last read physics, haha. :p

But yeah, it should be correct.

*Laurelindo*
08-31-2011, 05:41 PM
Thanks a lot.
I'm playing around with physics questions right now for fun, so I might ask some more later. :D