NOVA Online | Voyage of Doom | Balloon-in-Car Puzzler

Balloon-in-Car Puzzler
Puzzler 1

You're sitting in a car that's not moving. Also in the car is a helium-filled balloon, which is resting up against the car's ceiling somewhere near its middle. The driver hits the gas and the car accelerates forward. You're thrown back into your seat.

What happens to the balloon? (Before you answer, think about what will make the balloon act the way you think it will.)

It floats toward the back of the car.
It floats toward the front of the car.
It stays put.