epäinertiaalinen

Epäinertiaalinen refers to a frame of reference that is accelerating. In physics, an inertial frame of reference is one that is not accelerating. In an inertial frame, Newton's first law of motion, the law of inertia, holds true: an object at rest stays at rest, and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.

In contrast, an epäinertiaalinen frame of reference is one that is accelerating, either linearly or rotationally. In such frames, fictitious forces, also known as inertial forces, appear to act on objects. These forces are not real in the sense that they are not caused by interactions with other objects, but rather they are a consequence of the observer's own accelerated motion. Examples of fictitious forces include the Coriolis force and the centrifugal force.

For instance, if you are in a car that is accelerating forward, you feel pushed back into your seat. This sensation is due to the fictitious force. Similarly, if you are on a spinning merry-go-round, you feel a force pushing you outwards, which is the centrifugal force. These fictitious forces are crucial for describing motion within epäinertiaalinen frames of reference, allowing physicists to apply Newton's laws, albeit with these additional terms. Understanding the distinction between inertial and epäinertiaalinen frames is fundamental to classical mechanics and relativity.