Final answer:
Before releasing the Gravity Racers, they possess gravitational potential energy, which converts to kinetic energy as they descend.
Step-by-step explanation:
The form of energy present before letting the Gravity Racers go is gravitational potential energy. This energy is stored due to the position of the Gravity Racer at a certain height above the ground. When the racer is released, this potential energy is converted into kinetic energy as it moves down the slope.
The conversion of energy from potential to kinetic in the Gravity Racers illustrates the conservation of mechanical energy, where the total mechanical energy (potential plus kinetic) remains constant in the absence of friction and air resistance.