Answer: [tex]1.875\ rad/s^2, 8\ s[/tex]
Explanation:
Given
Radius of disc [tex]r=10\ cm[/tex]
Angle turned [tex]\theta=60\ rad[/tex]
Initial angular velocity [tex]\omega_0=0[/tex]
Final angular velocity [tex]\omega_f=15\ rad/s[/tex]
using [tex]\omega^2-\omega_o^2=2\alpha \cdot \theta[/tex]
Substitute values
[tex]\Rightarrow 15^2-0=2\times \alpha \times 60\\\Rightarrow \alpha=1.875\ rad/s^2[/tex]
using [tex]\omega=\omega_o+\alpha t[/tex]
Substitute values
[tex]\Rightarrow 15=0+1.875\times t\\\Rightarrow t=8\ s[/tex]
