Is Motion a Change of Direction? Physics Clarification

No. Motion is a change in position over time. Direction change is acceleration (specifically, centripetal acceleration).

Key Distinctions

• Uniform Linear Motion: Constant velocity (speed + direction) → motion without direction change (e.g., car on straight highway at 60 mph)
• Uniform Circular Motion: Constant speed, continuously changing direction → acceleration toward center
• Acceleration: Any change in velocity (magnitude or direction)

Newton's First Law

An object in motion stays in motion in a straight line unless acted upon by a net force. Force causes acceleration (direction/speed change). No force = no direction change.

Everyday Example

A satellite orbiting Earth: constant speed, constantly changing direction (accelerating due to gravity). A hockey puck on frictionless ice: constant velocity, no direction change.