
Answer:
angular acceleration = 1.67 rad/s²
Explanation:
given data
door wide = 1 m
initially ope angle = 30°
push force = 20 N
rotational inertia = 3.0 kg m²
solution
we apply force at middle so length will be here r1 = [tex]\frac{1}{2}[/tex] Â = 0.5 m
and
now we get here torque that is express as
torque Ď„ = Force Ă— r1 Ă— sin30 Â ......................1
put her value and we get
torque Ď„ = 20 Ă— 0.5 Ă— sin30
torque Ď„ = 5 Nm
and  we know
torque = rotational inertia × angular acceleration  .......................2
put her value and we get angular acceleration
angular acceleration = [tex]\frac{5}{3}[/tex] Â
angular acceleration = 1.67 rad/s²