To find the linear acceleration without the radius given, you need additional information. Specifically, you need either the radius or the angular acceleration.
If you have the angular acceleration (α) in addition to the final (ωf) and initial (ωi) angular velocities, you can use the following formula to calculate the linear acceleration (a):
a = α * r
where: a is the linear acceleration, α is the angular acceleration, and r is the radius of the circular path.
This formula relates the angular acceleration to the linear acceleration by multiplying the angular acceleration by the radius of the circular path. The linear acceleration represents the acceleration of an object moving along the circular path at a specific radius.
If you have the radius, you can use the formula above. However, if the radius is not given and the angular acceleration is also not provided, it is not possible to calculate the linear acceleration without additional information.