The soda bottle rocket car is powered by compressed air and is an excellent example for demonstrating action-reaction for Newton’s 3rd law of motion. The water inside the bottle also demonstrates Newton's first law. It has inertia and collects at the back of the bottle as as it suddenly accelerates forward. The soda bottle is pumped up to about 75 PSI with air using a portable air pump. When launched the air pushes water out the mouth of the bottle to incredible speed. The bottles are able to withstand higher pressures but the pump maxes out at this range. On a good run without hitting a wall it can travel well over 100 feet.