In circular motion, the kinetic energy formula 1/2 m v^2 is applicable for point masses, such as those at the end of a massless string. For more complex objects, the moment of inertia and rotational kinetic energy must be considered. The kinetic energy is dependent on the speed squared, not the direction of travel, which is crucial in circular motion. For further understanding, exploring the concept of a "Physical Pendulum" is recommended. Overall, the applicability of the formula varies based on the object's characteristics.