# Angular acceleration x radius= Acceleration of center of mass ?

1. Nov 24, 2013

### AakashPandita

For a rotating body,
(angular acceleration x radius)= Acceleration of center of mass ?

But a rotating body can have angular acc. even if it is not translating. what is wrong?

2. Nov 24, 2013

### Kishlay

no no no........... angular acc. x radius = the linear acc. of a point on the body , ie the tangential velociti of that point with respect to the centre of mass

3. Nov 24, 2013

### Kishlay

the point is moving around the body with a speed= R x α
where α= angular acceleration

4. Nov 24, 2013

### Tanya Sharma

Hi Aakash...

The correct relationship for a point on a rotating body is

atan = αr where ,

atan=tangential acceleration of the point with respect to center of the axis

α = angular acceleration of the rotating body

r= distance between the point and the center of the axis

The relationship acm = αr is a constraint which is sometimes obtained in cases when a body is rotating as well as translating.

For eg. a sphere rolling without slipping on floor .

5. Nov 24, 2013

### Kishlay

i have told the same........

6. Nov 24, 2013

### Tanya Sharma

Your language is sloppy and inaccurate .

The item in red should be acceleration.

Again ,instead of center of mass,you should have used center of rotation.

That doesn't make any sense . Neither the point is moving around the body ,nor is speed equal to R x α

7. Nov 24, 2013

thanks.