Motion in science, specifically in physics, is defined as the change in position or orientation of a body with respect to time and a frame of reference. This means an object is said to be in motion if it changes its position relative to something considered stationary, called the frame of reference
. There are different types of motion:
- Translation : motion along a line or curve where all points of the body move the same distance.
- Rotation : motion where the orientation of the body changes, with all points rotating around an axis.
- A combination of both translation and rotation can occur simultaneously
Motion is described using quantities such as distance, displacement, speed, velocity, and acceleration. Distance is the total path covered, while displacement is the change in position from the starting point. Speed is how fast an object moves, and velocity is speed with a direction. Acceleration is the rate of change of velocity over time
. Newton's laws of motion provide the fundamental principles governing motion:
- An object remains at rest or in uniform motion in a straight line unless acted upon by a net external force (law of inertia).
- The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass (F = ma).
- For every action, there is an equal and opposite reaction
Motion is relative, meaning it depends on the observer's frame of reference. For example, a car may appear stationary to someone inside it but moving to an observer on the ground
. In summary, motion in science is the continuous change in position or orientation of an object relative to a frame of reference, described and predicted by physical laws such as Newton's laws of motion
