Brain Teasers
Lost Cargo
Mad Ade is on a barge in a lock on a canal. The lock is 25 feet long, 12 feet wide and 20 feet deep. It holds enough water to reach the 10 foot level normally. With the barge, the water is at the 13 foot level. Your cargo is concrete blocks that are 6 inches cubed, and Mad Ade has just accidentally dropped 800 of them overboard. By how much would the water level rise?
Answer
It wouldn't rise at all. The weight of the blocks when aboard the barge had already made the level rise, dropping them overboard would make the barge lighter, but the water level would remain constant, because the weight has only transferred from the barge to the actual water.Hide Answer Show Answer
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The water would rise because the blocks fall into it, and it would rise an amount of water equal to the volume of the bricks.
The boat however would rise out of the water and hence the water would go down by an amount of water equal to the weight of the blocks.
I'm presuming these concrete blocks are more dense than the water, so the water level will decrease
The boat however would rise out of the water and hence the water would go down by an amount of water equal to the weight of the blocks.
I'm presuming these concrete blocks are more dense than the water, so the water level will decrease
All i can say is that according to a puzzle set by mensa, regarding a boat in a pond and the occupants falling over board, they stated in there answer that the water will not rise because the weight of the occupants had already displaced the water when on the boat. The fact that the occupants jumped over board only lessened the weight in the boat, not the actual volume of water displaced. If you don't agree all i can suggest is that you contact mensa to explain it in more detail.
A floating object displaces its weight and a submerged object displaces its volume.
This is to do with density. Imagine a substance so dense that it is only 1 cubic meter, but it is so heavy it can drop an ocean liner a half meter into the water, displacing tonnes of water. If you throw this overboard, the liner rises half a meter, but the water only increses by the 1 cubic meter. (Obviously an exaggerated situation, but you can see the idea)
MENSA are wrong! (I also queried another of their "puzzles" and am waiting on an answer. Where is this puzzle found?
MENSA are wrong! (I also queried another of their "puzzles" and am waiting on an answer. Where is this puzzle found?
So what you are really saying Ade, is that you just copied the puzzle, and didn't think it up. Figures.
Andy, obviously you can't read, other wise you would have seen that in my comment i explain a completly different puzzle from mensa about people falling into a pond, on which I based my teaser. As you can see my teaser has been adapted and changed significantly. A large amount of puzzle on this site are copied word for word from other sites or books, at least I tried to make an existing puzzle different, by changing the situation and features. I didn't copy another puzzle, i was inspired to create my own based on an existing idea.
Oh my god, everyone take note, I have to AGREE with Mad'ade about the origins of this puzzle. I've said all along that outside inspiration is a good thing as long as its only inspiration and direct plaguarism. This puzzle passes muster. But on the other hand,Cathal is right on the physics side. Your answer is incorrect Mad'ade.
What? Did you think I could let that praise go by unchecked? hehe
What? Did you think I could let that praise go by unchecked? hehe
I think i've heard this puzzle before in a Car Talk puzzle book. but in that answer, the water level sinks, i think. I wonder, why hasn't anyone ever tried doing dumping the cargo overboard and watching the water level? it would finally solve this puzzle. Probably because no one really cares, but it's a fun thing to puzzle over. Raynee, my gravy, you agreed with mad-ade. i was incredibly surprised. hehehe.
I understand now, if you did copy it from a Mensa puzzle, but changed the fact that it was people falling out of the boat, then thats why you screwed this up. If it were people, the people would float, and therefore only displace a volume of water equal to the volume the water level dropped.
Maybe you should have just ripped it off directly!
Maybe you should have just ripped it off directly!
maybe I will next time , just to please you Cathal. At least I tried to be more than just a submitter that copies word for word, like so many others, but if i fail then i failed alone, and I shall bear the burden knowing that at least i had the guts to try, which is more than most would even attempt.
If you had thoguht up something yourself, then you might have actually thoguht about it. It might actually have been good and interesting and fun.
How can you say you only got "inspiration" from the mensa puzzle? You did no thinking of your own about this (which is probably why you screwed it up). You obviously didn't understand the Mensa puzzle, and why it is so clever. You didn't fail alone, you copied of someone else, and still messed up. Get off your high horse and admit it, because we can all see through it.
How can you say you only got "inspiration" from the mensa puzzle? You did no thinking of your own about this (which is probably why you screwed it up). You obviously didn't understand the Mensa puzzle, and why it is so clever. You didn't fail alone, you copied of someone else, and still messed up. Get off your high horse and admit it, because we can all see through it.
so what do you want Cathal? Do you want me to admit to copying a teaser, ok I will if you do. I took the liberty of reading your teasers today and wow what a collection of second hand oldies you have. Like for example LOTTERY ODDS(printed in the national press when the lottery began), or GAME OF DARTS (which is incorrect any way, check comment box ) DOGS (I did this at school, and I left over 15 years ago), SHIP AND BOILER(again school room math), MONEY IN WATER(even down to the euro) FALLEN SIGN (same situation different names) TRICKY MATHS SYMBOLS (my 9 year old son had this in his home work last year) GRAZING COWS ( an old mensa favourite) and UPSIDE DOWN CAR (copyied directly from a magazine article, see bluetwos comments) I could delve deeper, but I think that is enough for now. Feel free to carry on stalking me, it's quite flattering, but just remember when you start slinging mud, expect some to stick!
At least I understand my puzzles. I took my inspiration for most of my probability puzzles by noticing the mistakes other people make on this site. The basis for it obviously comes from any maths I studied anywhere, but I haven't that good of a memory to copy specific questions from my school days. I don't know how you can say I copied the symbols puzzle. I've seen the type of puzzle where you need to work out what the symbols mean, but that is my own. It actually annoys me quite a lot for you to say I copied it because it took me quite a while to come up with that. It wasn't easy to get it right and anyone who can do it would appreciate it, but I'm fairly confident you would not be included in that group. I even e-mailed RayneeDay with it because I wasn't sure it made sense before I submitted it. He appreciated it. I've thought about the car thing a lot too, I read the same comment, I'm Irish, I don't know what R+T is (a car magazine I presume). I've never seen this explained before and I've actually had that posted a while now so check your date on that magazine first. I've seen the idea of a cow grazing, but at least I made up my own and what do you mean MONEY IN "WATER(even down to the euro)"???? School room maths for you 15 years ago in Euros? I'd say thats fairly advanced!
Somebody complained because the lottery thing doesn't apply to America because they have different numbers (more I presume). At least I can do all my puzzles. If you look at the mistakes I do make (which I can admit I make a mistake) then its probably fairly clear that I am trying to make up the puzzle myself, be it by a silly adding mistake, of not enough time spent thinking about it. Good luck to you if you think other wise. Are you annoyed becase I posted a link to you BRICKS which shows where you copied it from?
I can say that I didn't come up with all of my puzzles, some I remember being told years ago or at least the same idea even if I can't remember it word for more, but at least I can understand them. Its quite annoying when you say something like this after my time I spent thinking about good puzzles for the benifit of other people who are interested in doing them. (Like the square island I remember something like that from years ago) Its good if someone likes something from ages ago, but its not very satisfactory because I didn't write it first. People who comment "Yeah that was nice" or whatever make it all worthwhile. People like you make it all worthless when you have a go because you were found out.
I don't think you could take satisfaction from any of your puzzles.
Its funny all the ones you picked are my own.
Somebody complained because the lottery thing doesn't apply to America because they have different numbers (more I presume). At least I can do all my puzzles. If you look at the mistakes I do make (which I can admit I make a mistake) then its probably fairly clear that I am trying to make up the puzzle myself, be it by a silly adding mistake, of not enough time spent thinking about it. Good luck to you if you think other wise. Are you annoyed becase I posted a link to you BRICKS which shows where you copied it from?
I can say that I didn't come up with all of my puzzles, some I remember being told years ago or at least the same idea even if I can't remember it word for more, but at least I can understand them. Its quite annoying when you say something like this after my time I spent thinking about good puzzles for the benifit of other people who are interested in doing them. (Like the square island I remember something like that from years ago) Its good if someone likes something from ages ago, but its not very satisfactory because I didn't write it first. People who comment "Yeah that was nice" or whatever make it all worthwhile. People like you make it all worthless when you have a go because you were found out.
I don't think you could take satisfaction from any of your puzzles.
Its funny all the ones you picked are my own.
Hello, Cathal, you still insisting on stalking me. Have you no real friends? In your latest comment you state that you understand your teasers??? Is this why the darts one is wrong?? Also I never said that the Eruo question was from my school days, It certainly doesn't say so in my comments, I just state that i have seen the teaser before, using the same euros coins. Don't be so conceited to proffess that all your teasers are original, and then say that they are from teaser you heard years ago??? (KETTLE, POT, BLACK. ring any bells) as for your link to another site on my teaser, thanks, Their teaser was posted 8 days after mine. Oh yeah, as for your upside down car teaser you posted it a fortnight ago, not "awhile ago" like you claimed (guilty concience, perhaps?). I would say that less than 20% of all teaser on this site are totally original, the majority are just reinvented and repackaged, like mine was, although i openly admit my knowledge of physic lead me to misinterpret the answer, big deal, I have already admitted to that. I noticed that this isn't your real issue, you like to post comments pulling down other work, but you start to cry and lash out wildly when it is returned. I made a mistake and was big enought to admit it, what else do you want. None of us are perfect, I shall not be dragged down to your level, I mean how can you say that a feature about the lottery that appeared in all the national papers regarding the odds on the lottery, is one of your own?
Get off your high horse, its a long way to fall. We have both made mistakes, only I am big enough to admit to mine.
Get off your high horse, its a long way to fall. We have both made mistakes, only I am big enough to admit to mine.
Stalking??? OK last comment then. I'm not American, I don't read your national papers, although I'm fairly certain that lots of people have already worked out the odds of winning the lotto. At least I didn't copy and paste, at least I did the work myself and understand it. I thought it might be something people would be interested in, thats why I submitted it. If I knew everyone knows this I wouldn't have bothered.
Question. How many numbers in American Lotto? I think its 42 here in Ireland, so thats what I based my solution on.
I would imagine that its more numbers in America, if I copied it why would I not leave it the same.
I also don't know what the car magazine is I'm supposed to have copied out of, american publication again? This is something I worked out for a physics class about 5 years ago. If you look at my solution its fairly vague, if I had copied, I'm sure I would have had all the facts and figures.
I doubt your nine year old kid could could do my maths. I doubt most people could do it. I would like to see a copy of his maths book to, because it would be an amazing coincidence if I made up the exact same puzzle.
I got my darts wrong because I didn't spend enough time thinking about it. I rushed through it. If I had copied, would I not have got the right answer?
As another mistake I made with a simplified maths symbol type where I did something stupid like added 1+1 and got 3, which made the puzzle unsolvable.
If I had copied would I not have had it right?
Just because 80% of things are copied doesn't mean its OK. But here are the problems when people do copy. You diddn't even understand the puzzle you copied, and you screwed up what would have been a very clever puzzle. (Clever because most people may get it right but for the wrong reason, but the really clever people would appreciate how nicely it works out.) Thats probably what annoys me most, and that is the worst typ of copying. When somebody rips something off, trying to claim it as their own, and screw it up because of the "renaming" they do.
Question. How many numbers in American Lotto? I think its 42 here in Ireland, so thats what I based my solution on.
I would imagine that its more numbers in America, if I copied it why would I not leave it the same.
I also don't know what the car magazine is I'm supposed to have copied out of, american publication again? This is something I worked out for a physics class about 5 years ago. If you look at my solution its fairly vague, if I had copied, I'm sure I would have had all the facts and figures.
I doubt your nine year old kid could could do my maths. I doubt most people could do it. I would like to see a copy of his maths book to, because it would be an amazing coincidence if I made up the exact same puzzle.
I got my darts wrong because I didn't spend enough time thinking about it. I rushed through it. If I had copied, would I not have got the right answer?
As another mistake I made with a simplified maths symbol type where I did something stupid like added 1+1 and got 3, which made the puzzle unsolvable.
If I had copied would I not have had it right?
Just because 80% of things are copied doesn't mean its OK. But here are the problems when people do copy. You diddn't even understand the puzzle you copied, and you screwed up what would have been a very clever puzzle. (Clever because most people may get it right but for the wrong reason, but the really clever people would appreciate how nicely it works out.) Thats probably what annoys me most, and that is the worst typ of copying. When somebody rips something off, trying to claim it as their own, and screw it up because of the "renaming" they do.
im English, so there fore we do share the same national paper or at least some of them. as for the rest of your comment, what is your problem, I said I was wrong, now grow up and get a grip on life. You made mistakes, i made mistakes, big deal, thats life. If it bothers you that much get some therapy!! I really don't know how you can rant on so much about how you may have got some of your teaser wrong because you made a mistake, then critise some one else for doing the same? Obviously you also have a short memory other wise you would have remembered that I said the reason I got this teaser wrong is because I tried to create my own using a formula that I didn'y fully understand, and like you yourself point out If i had "copy and Pasted" it, well we wouldn't be having this conversation in the first place would we? think about it! it is only because i tried to emulate a subject that I didn't fully understand.It may have been a pre used Idea,like so many others on this site, but at least i tried to make it original, by changing the names, places, situations and outcome. Now be a good boy, accept my admission of error, like i have admitted so many times it has become boring, and get on with your life, as I will do mine.
Why is everybody except Andy1608 writing in paragraphs? I am really freaked out here ok? Ahhhhhhhh......
BTW I wonder if you still think your 9 year old did my TRICKY MATHS SYMBOLS at school!
something similar to it at least.
I tried to post a similar problem and had it rejected as a duplicate. At least mine was original and had the correct answer!
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