What is the net acceleration of the coin on a rotating disk?

[ComputerForests000]

Homework Statement

A disk is initially at rest. A penny is placed on it at a distance of 1.4 m from the rotation axis. At time t=0s, the disk begins to rotate with a constant angular acceleration of 1.9 rad/s^2 around a fixed, vertical axis through it's center and perpendicular to it's plane. Find the magnitude of the net acceleration of the coin at t=1.2 seconds.

Homework Equations

tangential acceleration=α r
radial acceleration= r ω^2
ω = ω initial + α t

The Attempt at a Solution

I found the tangential acceleration to be 2.66 m/s^2,
then used ω = ω initial + α t to find the angular velocity, 3.192 m/s,
then found the radial acceleration to be 14.2644 m/s^2,
then took the square root of (tangential acceleration)^2 +(radial acceleration)^2 , which came out to be:
14.51 m/s^2
Apparently this answer is incorrect.

 

[Delta2]

Something is wrong with the calculation of angular velocity (you also report it in units m/s which is also wrong), I calculated that is equal to 2.28 rad/s at time t=1.2s.

 

[haruspex]

to find the angular velocity, 3.192 m/s,

That's the tangential velocity, not the angular velocity.