Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Velocity vector's change of direction

  1. Oct 26, 2005 #1

    If an object changes it's direction but not speed, then velocity vector will only change its direction but not magnitude.

    * ... delta

    *r... displacement vector

    Formula for velocity change is *v = *r / *time

    This formula doesn't tell us anything about the direction of *v, it tells us
    only about its magnitude ?

    Same could be said for acceleration vector a. Formula will only tell you acceleration vector's magnitude, but not it's direction ( well we do know the direction is same as *v, but since we don't know the direction of *v it's of little use ) ?

  2. jcsd
  3. Oct 26, 2005 #2


    User Avatar
    Science Advisor
    Homework Helper

    The correct "formulas" are

    [tex]\vec v = \frac {d \vec r}{dt}[/tex]

    [tex]\vec a = \frac {d \vec v}{dt}[/tex]

    These are vector quantities. If the direction of the velocity changes without changing the speed, the velocity and acceleration are perpendicular to each other.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook