# Speed vs. Velocity

## Key Formulas

v | velocity | m/s | |

Δx | displacement | m | |

Δt | elapsed time | s |

s | speed | m/s | |

d | distance | m | |

Δt | elapsed time | s |

## Tips to Remember

- Velocity is a
*vector*quantity. That means it has both magnitude (how fast) and direction. Sometimes the direction isn’t obviously given, but it’s buried in the sign of the velocity. For example, a velocity of 6 m/s doesn't have an obvious direction like up or east, but it is in the*positive*direction, as opposed to -6 m/s, which would be in the opposite direction. - Speed is a
*scalar*quantity. That means that it has only magnitude; the direction is not included. Speed will always be positive, since a negative speed would imply a direction. - Since velocity is a vector, it depends on displacement, which is also a vector. Similarly, speed depends on distance, which is a scalar like itself. Displacement takes direction into account, but distance does not. That means that if someone walks 7 m east, then 4 m west, her displacement is 7 + (-4), or 3 m. The distance she covers is 7 + 3, or 10 m. The direction change in the 4 m leg caused a negative displacement, but not a negative distance, since distance is
*always*positive. - The displacement is the difference between the object’s starting and ending positions. That means that if someone walks around a track and returns to her starting point, her displacement is zero.

# Book Recommendation

Disclosure: As an Amazon affiliate, I earn a commission on sales of this item.