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๐ŸƒSpeed vs Velocity๐Ÿงญ

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

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๐ŸƒSpeed
  • โœ“Measures how fast an object moves
  • โœ“A scalar quantity โ€” magnitude only, no direction
  • โœ“Always positive or zero
  • โœ“Average speed equals total distance over total time
  • โœ“Used in everyday descriptions of motion
๐ŸงญVelocity
  • โœ“Measures speed together with direction of motion
  • โœ“A vector quantity โ€” has both magnitude and direction
  • โœ“Can be positive, negative or zero
  • โœ“Average velocity equals displacement over time
  • โœ“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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