Posted: 3/19/2012 9:29:21 PM EDT
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Post your favorite science type brainteasers. No googling is allowed.
I'll start: You are driving your car to your son/daughters birthday party. In the back you have a bunch of helium balloons. You come up to a red light and use the brakes to come to a stop. What do the balloons do? Stay still, move to the front, or move to the back? Why? I'll give you a half hour before I post the answer. If you already have heard this before refrain from posting. |
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The balloons will move forward in relation to the car, but the dynamics are a little messy because they're in a resistant volume of air which is standing relatively still in relation to the car.
Here's a math teaser. If you take a perfect octagon and draw a dot on the middle of each of the 8 sides, can you form a perfect circle connecting all the dots? And, if so, would the circumference of that circle be the same as the perimeter of the octagon? |
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No idea. Are the balloons touching the ceiling or floating freely? Are the balloons attached to strings? If the balloons are attached to strings, are those strings anchored? The force of the stop will cause the balloons to go forward. The questions above will determine what happens next. |
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They move backwards. Helium is less dense than air, think of the the vehicle as essentially a container for that "fluid". The air mass in the vehicle moves forward which causes the balloon to float to the top(which is the back).
Best way I can explain it. Wouldn't have believed it if I had not seen it for my own eyes. |
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Damnit, read the OP and actually knew the answer. It will probably take years for that worthless trivia to come around again.
As far as proof for the poster above, I've done it and seen it first hand. That was the result of a debate that spiraled out of control. |
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Damnit, read the OP and actually knew the answer. It will probably take years for that worthless trivia to come around again. As far as proof for the poster above, I've done it and seen it first hand. That was the result of a debate that spiraled out of control. Nice, heh. |
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May I add an addendum? KeithJ is banned from this thread. 
The ballons will move forward, following newtons law (the whole "object in motion tends to stay in motion" thing) Wrong. The balloons will move counter-intuitively: They will move to the BACK of the car, because the air pressure is changing, i.e. it becomes higher toward the front of the car. I remember seeing this many years ago when my dad was driving. |
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The balloons will move forward in relation to the car, but the dynamics are a little messy because they're in a resistant volume of air which is standing relatively still in relation to the car. Here's a math teaser. If you take a perfect octagon and draw a dot on the middle of each of the 8 sides, can you form a perfect circle connecting all the dots? And, if so, would the circumference of that circle be the same as the perimeter of the octagon? Yes and no. |
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Quoted: If you take a perfect octagon and draw a dot on the middle of each of the 8 sides, can you form a perfect circle connecting all the dots? And, if so, would the circumference of that circle be the same as the perimeter of the octagon? Since the circle would be completely inside the octagon (aside from touching at 8 points), who would possibly think the circumference of the circle would be the same as the perimeter of the octagon? |
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What are most packing peanuts made of? cornstarch. Yup. I polled my entire facility one day, not one manager or engineer or tech person knew. The test mechanic and janitor both did. Looks on faces when I popped them in my mouth and started chewing = Priceless. |
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If you take a perfect octagon and draw a dot on the middle of each of the 8 sides, can you form a perfect circle connecting all the dots? And, if so, would the circumference of that circle be the same as the perimeter of the octagon? Since the circle would be completely inside the octagon (aside from touching at 8 points), who would possibly think the circumference of the circle would be the same as the perimeter of the octagon? Hmm, you're right. Maybe I was thinking of the quarterpoints on each side rather than the midpoints... So, dots at the 1/4 and 3/4 points on each side? |
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What are most packing peanuts made of? cornstarch. Yup. I polled my entire facility one day, not one manager or engineer or tech person knew. The test mechanic and janitor both did. Looks on faces when I popped them in my mouth and started chewing = Priceless. So that's why they dissolve under the faucet... |
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Balloons keep moving, but they do not move to the front. They catch up to the front of the car, which has decelerated more than the balloons.
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The balloons will move forward in relation to the car, but the dynamics are a little messy because they're in a resistant volume of air which is standing relatively still in relation to the car. Here's a math teaser. If you take a perfect octagon and draw a dot on the middle of each of the 8 sides, can you form a perfect circle connecting all the dots? And, if so, would the circumference of that circle be the same as the perimeter of the octagon? A circle would include all the points you described. The definition of a circle is the set of all points at a given distance from a central point. A circle is also the least perimeter per unit of area of any shape, so any other shape with a similar area must have a greater perimeter. |