# How is tangential accleration zero in uniform circular motion?

1. Sep 2, 2011

### pcsx22

How is tangential accleration zero in uniform circular motion??

1. The problem statement, all variables and given/known data
the magnitude of tangential velocity is same but the directions are different..so how can the tangential acceleration be zero??

2. Relevant equations

3. The attempt at a solution

2. Sep 2, 2011

### Hootenanny

Staff Emeritus
Re: How is tangential accleration zero in uniform circular motion??

Welcome to Physics Forums.
I'm afraid that I don't understand the question.

3. Sep 2, 2011

### stallionx

Re: How is tangential accleration zero in uniform circular motion??

Acceleration vector would point to the center ( 0, 0 ) causing a radial(only) acceleration as in circular motion.

4. Sep 2, 2011

### Pi-Bond

Re: How is tangential accleration zero in uniform circular motion??

You just answered the question yourself; it's because the tangential velocity (magnitude) is the same. If there were any tangential acceleration, the magnitude would not be constant. The only acceleration in this case is normal acceleration (i.e. centripetal acceleration) which causes the direction to change.

5. Sep 2, 2011

### pcsx22

Re: How is tangential accleration zero in uniform circular motion??

if tangential acceleration is considered to be zero in uniform circular motion then why is uniform circular motion is called accelerated motion??

6. Sep 2, 2011

### Staff: Mentor

Re: How is tangential accleration zero in uniform circular motion??

The velocity vector continually changes direction. Any change in velocity, magnitude or direction, is an acceleration. In uniform circular motion, the magnitude (speed) doesn't change but the direction does. The tangential component of acceleration is zero, but the radial component is not.