Helium Balloon in Car
Science brain teasers require understanding of the physical or biological world and the laws that govern it.
A helium-filled balloon is tied to the floor of a car that makes a sharp right turn. Does the balloon tilt while the turn is made? If so, which way? The windows are closed so there is no connection with the outside air.
Because of buoyancy, the helium balloon on the string will want to move in the direction opposite the effective gravitational field existing in the car. Thus, when the car turns the corner, the balloon will deflect towards the inside of the turn.
Oct 16, 2001
|When the car starts going it will pull the balloon with it. When the car is at a set speed, the balloon will appear to be straight up to the viewer in the car because the car and balloon are both going at the same speed. When the car turns, the balloon will want to keep going the direction the car was going before it made the turn. To the viewer inside the car, the balloon will shoot off to the outside of the turn. To a viewer outside the car, the balloon will appear to go the same direction it was going before the car made the turn. When the turn is made, the balloon will be stopped by the rope and will be pulled around the turn with the car, thus creating the effect that the balloon is on the outside of the turn. (Phew)|
Dec 31, 2001
|Imagine the car crashing head-on into a tree. It's hard to believe that the balloon would not lurch forward with respect to the remains of the car. It's a little more dramatic, but a little easier to grasp.|
Apr 17, 2002
|Clay and Dufus are missing the point. Because a helium balloon is less dense than the air in the car, the AIR will be forced to the left of the car in a sharp right turn, pushing the less dense balloon to the right. |
It's the same deal if the car crashes - the air will "lurch" forward causing the balloon to travel backwards.
Look at a centrifuge - since it spins quickly in a circle, everything in the test tube should be forced to the outside of the circle, right? Wrong. Less dense materials move toward the inside of the circle relative to the more dense material. That's the whole point of a centrifuge.
Jun 05, 2002
|definately the inside of the turn, buoyancy, a beautiful thing|
Aug 14, 2002
|First two guys are totally off the mark. It's really cool to do with candles or some other sort of flame in a centerfuge. Yes, the balloon does have momentum, and it does continue in the same direction unless acted upon...blah blah blah, but so does everything else in the car, including the air that the balloon is less dense than, and it all happens at the same time, and then bouyancy does it's job.|
Jan 09, 2003
|Quite amazing... wow.|
Nov 20, 2003
|I'm glad I read Bobbrt's comment before I voted on this teaser, otherwise I would have voted it down. Good puzzle but "buoyancy" is insufficient reason to explain this unexpected outcome. |
Dec 13, 2005
|A great teaser, but after i read it i wasn't sure what you meant by "deflect;" hmm.. i thought it will hit the driver in the head if its in the fron seet!|
Oct 08, 2006
Oct 13, 2006
|I think its more because of inertia though.|
Dec 13, 2008
| This Teaser definitely makes you think about all the times you missed Physic class and lab. Don't Scream, but it seems to me the helium balloon being tied to the floor of the car, how many feet from the floor? What kind of balloon, rubber, or New paper type material? the size of the balloon. I know the balloon moves, but in what direction is complicated. I thought it remained straight, moving back and forth. Especially, if it could Hit the driver in his head. This was an Excellent Teaser. I am just having fun. |
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