You are in a van, moving forward down the road. The van is sealed and no air is flowing through. In the back compartment of the van is a balloon filled with helium, tethered to the floor of the van by a single string. You hit the brakes firmly, suddenly slowing the van. Which way does the balloon move and why?
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September 20, 2008, 09:38 PM
No firearm, then I'm not playing. :mad:
September 20, 2008, 09:46 PM
The balloon (or any mass) should move forward relative to the vehicle. It would also move downward because the tether forces it to move in an arc rather than a line.
September 20, 2008, 09:54 PM
When you hit the brakes, the air in the car moves forward due to its own inertia. As a result, the less dense helium balloon moves backward because it is displaced by the air. I've seen it happen.
September 20, 2008, 10:06 PM
Depends on how heavy the tether is. Is there slack in the tether?
September 20, 2008, 10:09 PM
I already shot the balloon so it basically stays where it is.