Answer:
The final angular speed is 0.223 rad/s
Explanation:
By the conservation of angular moment:
ΔL=0
L₁=L₂
L₁ is the initial angular moment
L₂ is the final angular moment
L₁ is given by:
As the door is at rest its angular moment is zero and the angular moment of mud can be considered as a point object, then:
where
r is the distance from the support point to the axis of rotation (the mud hits at the center of the door; r=0.5 m)
v is the speed
m is the mass of the mud
L₂ is given by:
ωf is the final angular speed
The moment of inertia of the door can be considered as a rectangular plate:
M is the mass of the door
W is the width of the door
The moment of inertia of the mud is:
Hence,