# Average Velocity and Final Instantaneous Velocity

## Main Question or Discussion Point

Suppose a body moving in a curved path at a constant speed would its average velocity for a specific time period equal its final instantaneous velocity at the end of this period ?

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Orodruin
Staff Emeritus
Homework Helper
Gold Member
No.

Consider a circular motion after one full rotation. The average velocity is zero (you returned to the original position!).

DEvens
Gold Member
To expand on what Orodruin said: Consider a mass moving in a circle at a constant speed. After one revolution it will have returned to the point it started. So its average velocity is zero. But its instantaneous velocity is clearly not zero.

So if we consider a circular path, I suppose that the instantaneous velocity will equal the constant speed since the magnitude of the displacement vector will equal the distance at some instance during the period ?

Nugatory
Mentor
So if we consider a circular path, I suppose that the instantaneous velocity will equal the constant speed since the magnitude of the displacement vector will equal the distance at some instance during the period ?
To be precise, the magnitude of the instantaneous velocity will equal the constant speed.
That's a bit of a tautology though, because speed is defined to be the magnitude of the velocity.

sophiecentaur