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What is velocity?

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Quick answer

Velocity is the speed of an object in a specific direction. Unlike speed, which is just a number, velocity tells you both how fast something moves and which way it's going — for example, 50 km/h heading east. Velocity = speed + direction. It's a vector quantity (magnitude and direction).

Key things to understand

  1. Velocity = speed + direction. It's a vector quantity (magnitude and direction).
  2. Two objects can have the same speed but different velocities if they move in different directions.
  3. A change in velocity — speeding up, slowing down, or changing direction — is acceleration.
  4. An object moving at constant speed in a circle has a changing velocity, because its direction keeps changing.

People also ask

How is velocity different from speed?
Speed is just how fast (a number); velocity is how fast in a particular direction. Going 30 km/h is a speed; going 30 km/h north is a velocity.
Can velocity change while speed stays the same?
Yes — if you turn a corner at a constant 30 km/h, your speed is unchanged but your direction (and so your velocity) changes.
What is the unit of velocity?
The same as speed — metres per second (m/s) or kilometres per hour (km/h) — but always with a direction stated.

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