# Homework Help: Tangential acceleration - radial acceleration

1. Apr 17, 2012

### finitefemmet

Hi,

I got a ball in a circualar motion on a frictionless table and in a uniform circle.
I need to calculate the tangential acceleration and radial acceleration.

What I know:

Tangential velocity: 0.50m/s^-1 (constant)

Are theese formulas right for this problem?

Radial acceleration = V^2 / r

Tangential acceleration = r*angular acceleration

Because I am confused when I mix tangential velocity with radial acceleration and so on.. and I need some help on how I can calculate the angula acceleration for the tangential acceleration.

Every bit of information would help alot!

Thanks

2. Apr 17, 2012

### dikmikkel

The tangential accelearation of a constant tangential velocity is always zero, because the change in velocity is zero. The formula for radial part is:
$\alpha = \dfrac{\text{d}\omega}{\text{d}t} = \dfrac{\text{d}^2\theta}{\text{d}t^2}$
And for tangential :
$\vec{a} = \dfrac{\text{d}\vec{v}}{\text{d}t} = \dfrac{\text{d}^2\vec{r}}{\text{d}t^2}$

3. Apr 17, 2012

### finitefemmet

Thanks that solved it for me;)