Final answer:
Using a constant frame rate in animation assumes uniform motion, where the object's position changes at a constant rate, or motion at a constant velocity. It also simplifies representing motion from an inertial reference frame perspective, where observations are consistent with Newton's laws of motion.
Step-by-step explanation:
When using a constant frame rate for each image in an animation sequence to portray motion, we are assuming that the motion being depicted is uniform. This means that the object's position is changing at a constant rate, reflecting motion at a constant velocity. During such motion, the velocity does not change because the acceleration is zero. However, if we consider motion at constant acceleration, then although the acceleration is constant, the velocity changes at a constant rate. In both scenarios, using a constant frame rate assumes that the changes in position or velocity (depending on the type of motion) occur evenly over each frame.
It is important to note that the concept of motion is relative and can appear differently from different reference frames. A reference frame is a perspective from which motion is observed. Whether the frame is inertial (not accelerating) or not will impact the observation of motion and, by extension, how animation sequences should be managed to accurately represent motion. In animations, a consistent frame rate is used to simulate the linear progression of motion as it would appear in an inertial reference frame.