Answer:
a.
b.
Explanation:
The change in tire's angular velocity is
[tex]\Delta\omega=\omega_f-\omega_i[/tex]
Now,
[tex]\begin{gathered} \omega_f=3.9\text{rad}/s \\ \omega_i=-3.9\text{rad}/s \end{gathered}[/tex]
Therefore,
[tex]\Delta\omega=3.9-(-3.9)[/tex]
[tex]\boxed{\Delta\omega=7.8\text{rad}/s\text{.}}[/tex]
Part B.
The average angular acceleration is given by
[tex]\alpha_{\text{avg}}=\frac{\Delta\omega}{\Delta t}[/tex]
Now,
[tex]\Delta\omega=7.8\text{rad}/s[/tex]
and
[tex]\Delta t=1.85s[/tex]
Therefore,
[tex]\alpha_{\text{avg}}=\frac{\Delta\omega}{\Delta t}=\frac{7.8}{1.85}[/tex]
[tex]\Rightarrow\boxed{\alpha_{\text{avg}}=4.22\text{rad}/s^2}[/tex]
which is our answer!
