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🏃Speed vs Velocity🧭

Speed and velocity both describe motion, but only one includes direction. That single difference matters enormously in physics.

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🏃Speed
  • Measures how fast an object moves
  • A scalar quantity — magnitude only, no direction
  • Always positive or zero
  • Average speed equals total distance over total time
  • Used in everyday descriptions of motion
🧭Velocity
  • Measures speed together with direction of motion
  • A vector quantity — has both magnitude and direction
  • Can be positive, negative or zero
  • Average velocity equals displacement over time
  • Essential for calculating acceleration and forces

Verdict

Speed answers 'how fast?'; velocity answers 'how fast and which way?'. A car driving in a circle at constant speed has constantly changing velocity. Physics problems usually need velocity.

Frequently asked

Can speed be negative?+

No. Speed is always positive or zero, since it ignores direction. Only velocity can be negative.

Can velocity change while speed stays constant?+

Yes. Moving in a circle at constant speed changes direction, so velocity changes continuously.

What is the difference between distance and displacement?+

Distance is total path length; displacement is the straight-line change in position, with direction.

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