How Does Angular Momentum Apply When a Door is Hit by Mud?

AI Thread Summary
The discussion focuses on applying the principles of angular momentum to a scenario where a door is struck by mud. The door, hinged on one side, is initially at rest and is impacted by mud moving perpendicular to it. Participants emphasize the need to use conservation of angular momentum rather than linear momentum due to the external forces acting on the hinge. The key equation discussed is angular momentum, expressed as mvr sin(theta), which relates to the door's motion after the impact. Understanding how to convert linear momentum from the mud into angular momentum for the door is crucial for solving the problem.
mvpshaq32
Messages
28
Reaction score
0

Homework Statement



A solid wood door 1.00 m wide and 2.00 m high is hinged along one side and has a total mass of 41.0 kg. Initially open and at rest, the door is struck at its center by a handful of sticky mud with mass 0.700 kg, traveling perpendicular to the door at 11.0 m/s just before impact.

Homework Equations



L=rmv=I(omega)

The Attempt at a Solution



I know I have to use conservation of momentum, but I have no idea how to set up the problem of turning linear momentum into angular momentum.
 
Physics news on Phys.org
You have to use conservation of linear and angular momentum.
 
rl.bhat said:
You have to use conservation of linear and angular momentum.

you cannot use conservation of linear momentum. The hinge will provide external force.
 
mvpshaq32 said:
I know I have to use conservation of momentum,

you have to use conservation of angular momentum.

mvpshaq32 said:
but I have no idea how to set up the problem of turning linear momentum into angular momentum.

angular momentum = mvr sin(theta)

find angular momentum of door about the axis and multiply with angular velocity to get angular momentum.
 
Kindly see the attached pdf. My attempt to solve it, is in it. I'm wondering if my solution is right. My idea is this: At any point of time, the ball may be assumed to be at an incline which is at an angle of θ(kindly see both the pics in the pdf file). The value of θ will continuously change and so will the value of friction. I'm not able to figure out, why my solution is wrong, if it is wrong .
TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...

Similar threads

Replies
1
Views
5K
Replies
6
Views
2K
Replies
8
Views
3K
Replies
2
Views
4K
Replies
1
Views
31K
Replies
1
Views
2K
Replies
9
Views
3K
Back
Top