Q3 of 53 Page 230

You are sitting in a stationary car. There is a helium balloon tied to its floor. You accelerate and obviously feel like you are being pushed backwards (against the direction of your accelerations). The balloon.

Helium is less denser than the air and so it is lighter then the air, so when the car is accelerated the air starts moving backwards but as the helium is lighter it is pushed forward by the air collecting at its back.

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