How does Newton's first law affect a balloon car?

Newton’s first law of motion explains why the car started moving and why the car came to a stop

Newton’s first law of motion explains why the car started moving and why the car came to a stop. Newton’s first law of motion states that an object at rest will remain at rest and an object that is moving at a constant velocity will continue moving at a constant velocity unless acted upon by an unbalanced force. When the Balloon Car started to roll, the air inside the balloon came in contact with the air on the outside. The air inside of the balloon pushed out against the air on the outside causing the balloon car to accelerate. About 40 seconds later the balloon car stopped. It stopped because the balloon had no more air to push against the air on the outside. Therefore the air inside the balloon and the outside air would be considered unbalanced. Newton’s first law of motion proves that once the car comes in contact with another force that is unbalanced, the car will move, but once the air inside of the car is gone, the air on the outside won’t have to fight with another force causing the car to come to a complete stop

• You can read that's answer on this blog: http://bcpbycdt.blogspot.co.id/2011/12/analysis-questions-e.html