Motion in One Dimension

Rest and motion are relative terms. Always mention the reference object or surroundings when the question asks for a clear explanation.

Distance is a scalar quantity and is never negative. Displacement is a vector quantity; it can be zero even when distance is not zero, such as after a complete round trip.

Average speed equals total distance divided by total time. Average velocity equals total displacement divided by total time.

Uniform acceleration means velocity changes by equal amounts in equal intervals of time. Use the three equations of motion only for this case.

ICSE graph questions often ask what a horizontal line, a sloping line, or a curved line means. Read the axes first; never treat a distance-time graph like a velocity-time graph.