Science brain teasers require understanding of the physical or biological world and the laws that govern it.
One class started to hold an activity in which three different lengths of straw attached to a fully blown up balloon and then a string was drawn through the straw, thus giving the balloon a railing in which it can move on. When the three balloons were let go all at the same time, the class went to see which one got there first. Try to figure out which balloon got there first using the following straw lengths:
Group 1: 5 cm
Group 2: 15 cm
Group 3: 25 cm
HintThink about friction and gravity.
Group 3's balloon got there first. Here's how it works: Gravity affects everything right? So since group 3's straw is the longest, less weight is distributed in any given area.
Feb 15, 2008
|I really don't understand this. Where does the string go?|
Feb 15, 2008
|I dont like it. It was worder poorly and makes no sense. Where is the straw supposed to be? Where does the string go? Where does it lead to? What direction does it go?(straight up / straight across / slanted)|
Feb 15, 2008
|I agree with the previous comments. I think it needs a diagram or better wording to explain where and how the balloons were going. I think this is probably a really interesting teaser, but just explained wrong.|
Feb 16, 2008
|I can't make any sense of this teaser. It is worded poorly, making it difficult to understand the set up of the experiment.|
Feb 17, 2008
just to tell you, the string is fastened to two objects in the room such as a chair or a doorknob.
Feb 18, 2008
|didn't make sence. Yes the wieght would be distributed more but the added surface area would cause added friction. Not enough info to even have an answer.|
Feb 19, 2008
|try it for urself and youll see|
Apr 14, 2008
|Rockstar, you might go back and edit this to make it clearer. I agree with the comments that it is poorly worded and hard to follow. It sounds like you have a clear picture in your mind of how it is supposed to work, but it isn't being conveyed. for example, the phrase "to see which one got there first" is unclear. Got where? Someone else asked: what is the string attached to at each end? Is the string flat or slanted? These questions need to be answered!|
Apr 16, 2008
Apr 24, 2008
|Does anybody besides rockstar understand what he was asking? If so could you explain it because it doesn't look like rockstar wants to fix it up.|
Apr 24, 2008
|Okay, I just saw rockstar's comment. Let me see if I understand this now:|
The straw is attached to the side of a balloon (running parallel with the top and bottom of the balloon).
A string is fed through the straw and then one end is tied to something such as a chair/door knob etc. and then the other end is tied some distance away at the same height in a way that the string is pulled tight and the straw will be able to slide along it.
The balloons are inflated and then released so they move the length of the string.
And you want to know which length of straw will get the balloon along the string the fastest (or was that the slowest? ...i can't remember).
Jun 17, 2008
|What about photons? Just kidding. |
Feb 11, 2009
|right and theres electrons, neutrons, atoms, molecules, protons, quarks, hydrogen, lithium, cesium, carbon, helium, iron, unununnium and all that good stuff...|
Mar 06, 2009
|It's not only confusing, but also wrong. At least, as worded.|
If the string is pulled taut, then it is possibly right, but there is no mention of it anywhere. If the string is somewhat loose, then the longer straw will likely bind on the string where it bends (which will always be at the straw, because the weight will pull it to the lowest point).
Apr 09, 2009
|There are unaccounted-for variables in this teaser, including friction and weight of the straw. A longer straw has more mass, thus will produce drag on the force of the balloon. The general concept is correct for a specific set of paramaters, but is not universally correct.|
For example, imagine if the straw were 20 feet long. Do you still think the longest straw would win the race?
Mar 09, 2011
|I have absolutely no idea what that meant. Judging from the comments, I'm not the only one. This is definitely a zero on a fun scale.|
Apr 25, 2011
|I think (though I have been wrong before), that the question also assumes that the weight of the straw is negligible.|
The point of this teaser appears to be that force distributed over a larger area has less friction per unit of surface area (mathematically obvious); but whether force is infinitely spread or point-source, the total force is still the same.
Doubtless I'm simply missing the point too.
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