Posted by **Kayla** on Monday, April 4, 2011 at 11:56am.

A disk of radius 12 cm, initially at rest, begins rotating about its axis with a constant angular acceleration of 7.8 rad/s2. What are the following values at t = 4.0 s?

(a) the angular velocity of the disk

(b) the tangential acceleration at and the centripetal acceleration ac of a point at the edge of the disk

at =

ac =

- Physics 203 ( College) -
**Kayla**, Tuesday, April 5, 2011 at 9:59am
I don't know how to find ac, but I can help you with at and angular velocity of the disk.

(a) (7.8 rad/s^2)/4.0s = 31.2=angular velocity

at=7.8*.12=0.936

- Physics 203 ( College) -
**Matthew**, Wednesday, April 6, 2011 at 1:46pm
Tangential acceleration is the instantaneous linear acceleration associated with the particle at distance (r) from the center of rotation.

thus

Centripetal Accel= (angular accel)(r)

- Physics 1301 -
**Peter**, Wednesday, April 6, 2011 at 7:07pm
ac = (omega^2)*(radius)

= (31.2^2)*(0.12 m)

= 116.8

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