Answer:
8 s
Explanation:
We are given that
Acceleration=[tex]\alpha=3 rad/s^2[/tex]
Time, t=4 s
Angle,[tex]\theta=120 rad[/tex]
Initial angular velocity,[tex]\omega_0=0 rad/s[/tex]
Let [tex]\omega[/tex] be the velocity at the start of this 4 s interval
We know that
[tex]\theta=\omega_0t+\frac{1}{2}\alpha t^2[/tex]
Using the formula
[tex]120=4\omega+\frac{1}{2}(3)(4)^2[/tex]
[tex]120=4\omega+24[/tex]
[tex]120-24=4\omega[/tex]
[tex]4\omega=96[/tex]
[tex]\omega=\frac{96}{4}=24rad/s[/tex]
[tex]t=\frac{\omega-\omega_0}{\alpha}=\frac{24-0}{3}=8 s[/tex]
t=8 s
