Final answer:
The centripetal force needed to maintain an object in circular motion depends on the mass, velocity, and radius of the orbit. It increases with mass and velocity, and decreases as the radius increases.
Step-by-step explanation:
The force needed to keep an object moving in a circle, known as the centripetal force, is crucial in determining the object's circular motion. According to Newton's second law of motion, this force is necessary to maintain constant acceleration (by changing direction) in uniform circular motion. The centripetal acceleration is towards the center of the circle and is directly proportional to the mass of the object and the square of its velocity, and inversely proportional to the radius of the circular path. Therefore, if other factors are constant, more force is required when the radius of the circular orbit is smaller, and less force is required as the radius increases.