Final answer:
An 800kg car traveling over a hill gains potential energy, does not necessarily lose kinetic energy if moving at constant speed, and does not undergo uniform circular motion unless it follows a circular path.
Step-by-step explanation:
An 800kg car traveling over a hill gains potential energy because it is moving to a higher elevation and the potential energy is directly related to the height in a gravitational field. The equation for gravitational potential energy is PE = mgh, where m is mass, g is the acceleration due to gravity, and h is the height above the reference point. If we assume that the speed of the car is constant as it travels over the hill, this would imply there are no net forces acting on the car in the direction of motion, and hence, it does not lose kinetic energy, which is a product of velocity and mass (KE = 0.5 * m * v2). Furthermore, unless the car is moving around a circular path, it does not undergo uniform circular motion, which is motion in a circle at constant speed and involves a net inward or centripetal force.