The Total solution for NCERT class 6-12
In Exercises 3.13 and 3.14, we have carefully distinguished betweenaverage speed and magnitude of average velocity. No such distinction isnecessary when weconsider the instantaneous speed andthe magnitude of velocity. The instantaneous speed is always equal to themagnitude of instantaneous velocity. Why?
Instantaneous velocityand instantaneous speed are equal for a small interval of time because themagnitude of the displacement is effectively equal to the distance travelled bythe particle.