Final answer:
Inertia causes the balloon car to resist changes to its state of rest or motion, propelling it forward when the air is released and maintaining that motion until opposed by friction.
Step-by-step explanation:
The concept of inertia plays a significant role in how a balloon car operates. Inertia is a physics principle stating that an object will remain at rest or in uniform motion in a straight line unless acted upon by an external force. When you inflate a balloon attached to a car and then release it, the air rushing out pushes the balloon car forward due to Newton's third law, which states that for every action, there is an equal and opposite reaction. The car moves in the opposite direction of the escaping air due to inertia, which keeps the car moving forward until other forces like friction or air resistance slow it down. The concept also applies when the balloon car is in motion, as it will continue moving forward until a force (like friction) stops it, demonstrating inertia as described in Newton's first law of motion.