Motion

Distance = total path length (scalar — only magnitude). Displacement = straight-line distance from start to end with direction (vector). Example: Run around a 400m track and return to start. Distance = 400m, Displacement = 0! Displacement can be negative if returning.

Speed = distance/time (scalar, always positive). Velocity = displacement/time (vector, can be +ve or -ve). Average speed = total distance/total time. Average velocity = total displacement/total time. Uniform motion: constant speed in straight line.

Acceleration = change in velocity/time = (v-u)/t. Positive: speeding up. Negative (deceleration/retardation): slowing down. SI unit: m/s². Uniform acceleration: constant change in velocity per unit time (object falling under gravity = 9.8 m/s²).

Distance-time graph: slope = speed. Flat = rest. Steeper = faster. Velocity-time graph: slope = acceleration. Area under graph = displacement. Uniform motion: straight line. Uniform acceleration: straight line with positive slope.