Finding the angle of the total acceleration of a point?

[JessicaJ283782]

A point on a rotating turntable 21.5 cm from the center accelerates from rest to a final speed of 0.740 m/s in 1.80 s. At t = 1.26 s,

I found:

Radial Acceleration: 1.25

Tangential Acceleration: .4096

Total Acceleration: 1.31


Now, I'm having problems finding the total acceleration angle?


I did:

.740/1.80=.411
tan^-1(.411/1.25) and I got 18.2, but that isn't right?

Thank you!

 

[haruspex]

You haven't specified a reference frame for the angle. Is it the angle to the radius or to some initial coordinate direction?
Assuming it's to the radius (or, equivalently, to the tangent), the speed has nothing to do with it. You have the radial and tangential components of the acceleration as a vector; you just need to figure out the direction of the vector.