A helium balloon is tied to the seat of a car. The doors and windows of the car is closed. If the car now starts moving, in which direction will the balloon move- front or back?
closed as too localized by David Zaslavsky♦ Oct 21 '12 at 14:58
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This is a very good question. I intend to do the experiment later.
I think the balloon will move forwards. The heavier molecules of air will tend to remain backwards due to inertia of rest. So it will occupy the place of the lighter helium balloon, making the helium balloon go forwards.