Instead of using frame-based movement, it is much better to base our movement on time. Time is guaranteed to be consistent throughout development and on all hardware, now and in the future. Whether our game is updating at three frames per second or 3,000 frames per second, one second will always be equal to one second.
Using time-based movement is great because it allows us to use equations that have existed for hundreds of years. We don't need to reinvent the wheel to simulate velocity and acceleration. As we said before, using a constant speed to move the player is OK for some games, but that isn't how real physics works. Cars and spaceships do not accelerate instantly. Gravity pulls you down faster and faster the longer ...
