part a)
Centripetal acceleration is given as
[tex]a_c = \omega^2 R[/tex]
[tex]0.80 = \omega^2 * 4[/tex]
[tex]\omega = 0.45 rad/s[/tex]
Now time period is given as
[tex]T = \frac{2\pi}{\omega}[/tex]
[tex]T = \frac{2\pi}{0.45}[/tex]
[tex]T = 14.04 s[/tex]
constant speed is given as
[tex]v = R \omega[/tex]
[tex]v = 4* 0.45 = 1.8 m/s[/tex]
part b)
now when she is at radius r = 2 m
centripetal acceleration is given as
[tex]a_c = \omega^2 R[/tex]
[tex]a_c = 0.45^2 * 2 = 0.405 m/s^2[/tex]
now the linear speed is given as
[tex]v = r\omega[/tex]
[tex]v = 2 * 0.45 = 0.9 m/s[/tex]